what is a review of literature in a research paper

Have a language expert improve your writing

Run a free plagiarism check in 10 minutes, generate accurate citations for free.

• Knowledge Base

Methodology

• How to Write a Literature Review | Guide, Examples, & Templates

How to Write a Literature Review | Guide, Examples, & Templates

Published on January 2, 2023 by Shona McCombes . Revised on September 11, 2023.

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research that you can later apply to your paper, thesis, or dissertation topic .

There are five key steps to writing a literature review:

• Search for relevant literature
• Evaluate sources
• Identify themes, debates, and gaps
• Outline the structure
• Write your literature review

A good literature review doesn’t just summarize sources—it analyzes, synthesizes , and critically evaluates to give a clear picture of the state of knowledge on the subject.

Instantly correct all language mistakes in your text

Upload your document to correct all your mistakes in minutes

Table of contents

What is the purpose of a literature review, examples of literature reviews, step 1 – search for relevant literature, step 2 – evaluate and select sources, step 3 – identify themes, debates, and gaps, step 4 – outline your literature review’s structure, step 5 – write your literature review, free lecture slides, other interesting articles, frequently asked questions, introduction.

• Quick Run-through
• Step 1 & 2

When you write a thesis , dissertation , or research paper , you will likely have to conduct a literature review to situate your research within existing knowledge. The literature review gives you a chance to:

• Demonstrate your familiarity with the topic and its scholarly context
• Develop a theoretical framework and methodology for your research
• Position your work in relation to other researchers and theorists
• Show how your research addresses a gap or contributes to a debate
• Evaluate the current state of research and demonstrate your knowledge of the scholarly debates around your topic.

Writing literature reviews is a particularly important skill if you want to apply for graduate school or pursue a career in research. We’ve written a step-by-step guide that you can follow below.

Here's why students love Scribbr's proofreading services

Discover proofreading & editing

Writing literature reviews can be quite challenging! A good starting point could be to look at some examples, depending on what kind of literature review you’d like to write.

• Example literature review #1: “Why Do People Migrate? A Review of the Theoretical Literature” ( Theoretical literature review about the development of economic migration theory from the 1950s to today.)
• Example literature review #2: “Literature review as a research methodology: An overview and guidelines” ( Methodological literature review about interdisciplinary knowledge acquisition and production.)
• Example literature review #3: “The Use of Technology in English Language Learning: A Literature Review” ( Thematic literature review about the effects of technology on language acquisition.)
• Example literature review #4: “Learners’ Listening Comprehension Difficulties in English Language Learning: A Literature Review” ( Chronological literature review about how the concept of listening skills has changed over time.)

You can also check out our templates with literature review examples and sample outlines at the links below.

Download Word doc Download Google doc

Before you begin searching for literature, you need a clearly defined topic .

If you are writing the literature review section of a dissertation or research paper, you will search for literature related to your research problem and questions .

Make a list of keywords

Start by creating a list of keywords related to your research question. Include each of the key concepts or variables you’re interested in, and list any synonyms and related terms. You can add to this list as you discover new keywords in the process of your literature search.

• Social media, Facebook, Instagram, Twitter, Snapchat, TikTok
• Body image, self-perception, self-esteem, mental health
• Generation Z, teenagers, adolescents, youth

Search for relevant sources

Use your keywords to begin searching for sources. Some useful databases to search for journals and articles include:

• Your university’s library catalogue
• Google Scholar
• Project Muse (humanities and social sciences)
• Medline (life sciences and biomedicine)
• EconLit (economics)
• Inspec (physics, engineering and computer science)

You can also use boolean operators to help narrow down your search.

Make sure to read the abstract to find out whether an article is relevant to your question. When you find a useful book or article, you can check the bibliography to find other relevant sources.

You likely won’t be able to read absolutely everything that has been written on your topic, so it will be necessary to evaluate which sources are most relevant to your research question.

For each publication, ask yourself:

• What question or problem is the author addressing?
• What are the key concepts and how are they defined?
• What are the key theories, models, and methods?
• Does the research use established frameworks or take an innovative approach?
• What are the results and conclusions of the study?
• How does the publication relate to other literature in the field? Does it confirm, add to, or challenge established knowledge?
• What are the strengths and weaknesses of the research?

Make sure the sources you use are credible , and make sure you read any landmark studies and major theories in your field of research.

You can use our template to summarize and evaluate sources you’re thinking about using. Click on either button below to download.

Take notes and cite your sources

As you read, you should also begin the writing process. Take notes that you can later incorporate into the text of your literature review.

It is important to keep track of your sources with citations to avoid plagiarism . It can be helpful to make an annotated bibliography , where you compile full citation information and write a paragraph of summary and analysis for each source. This helps you remember what you read and saves time later in the process.

The only proofreading tool specialized in correcting academic writing - try for free!

The academic proofreading tool has been trained on 1000s of academic texts and by native English editors. Making it the most accurate and reliable proofreading tool for students.

Try for free

To begin organizing your literature review’s argument and structure, be sure you understand the connections and relationships between the sources you’ve read. Based on your reading and notes, you can look for:

• Trends and patterns (in theory, method or results): do certain approaches become more or less popular over time?
• Themes: what questions or concepts recur across the literature?
• Debates, conflicts and contradictions: where do sources disagree?
• Pivotal publications: are there any influential theories or studies that changed the direction of the field?
• Gaps: what is missing from the literature? Are there weaknesses that need to be addressed?

This step will help you work out the structure of your literature review and (if applicable) show how your own research will contribute to existing knowledge.

• Most research has focused on young women.
• There is an increasing interest in the visual aspects of social media.
• But there is still a lack of robust research on highly visual platforms like Instagram and Snapchat—this is a gap that you could address in your own research.

There are various approaches to organizing the body of a literature review. Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

The simplest approach is to trace the development of the topic over time. However, if you choose this strategy, be careful to avoid simply listing and summarizing sources in order.

Try to analyze patterns, turning points and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred.

If you have found some recurring central themes, you can organize your literature review into subsections that address different aspects of the topic.

For example, if you are reviewing literature about inequalities in migrant health outcomes, key themes might include healthcare policy, language barriers, cultural attitudes, legal status, and economic access.

Methodological

If you draw your sources from different disciplines or fields that use a variety of research methods , you might want to compare the results and conclusions that emerge from different approaches. For example:

• Look at what results have emerged in qualitative versus quantitative research
• Discuss how the topic has been approached by empirical versus theoretical scholarship
• Divide the literature into sociological, historical, and cultural sources

Theoretical

A literature review is often the foundation for a theoretical framework . You can use it to discuss various theories, models, and definitions of key concepts.

You might argue for the relevance of a specific theoretical approach, or combine various theoretical concepts to create a framework for your research.

Like any other academic text , your literature review should have an introduction , a main body, and a conclusion . What you include in each depends on the objective of your literature review.

The introduction should clearly establish the focus and purpose of the literature review.

Depending on the length of your literature review, you might want to divide the body into subsections. You can use a subheading for each theme, time period, or methodological approach.

As you write, you can follow these tips:

• Summarize and synthesize: give an overview of the main points of each source and combine them into a coherent whole
• Analyze and interpret: don’t just paraphrase other researchers — add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
• Critically evaluate: mention the strengths and weaknesses of your sources
• Write in well-structured paragraphs: use transition words and topic sentences to draw connections, comparisons and contrasts

In the conclusion, you should summarize the key findings you have taken from the literature and emphasize their significance.

When you’ve finished writing and revising your literature review, don’t forget to proofread thoroughly before submitting. Not a language expert? Check out Scribbr’s professional proofreading services !

This article has been adapted into lecture slides that you can use to teach your students about writing a literature review.

Scribbr slides are free to use, customize, and distribute for educational purposes.

Open Google Slides Download PowerPoint

If you want to know more about the research process , methodology , research bias , or statistics , make sure to check out some of our other articles with explanations and examples.

• Sampling methods
• Simple random sampling
• Stratified sampling
• Cluster sampling
• Likert scales
• Reproducibility

 Statistics

• Null hypothesis
• Statistical power
• Probability distribution
• Effect size
• Poisson distribution

Research bias

• Optimism bias
• Cognitive bias
• Implicit bias
• Hawthorne effect
• Anchoring bias
• Explicit bias

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a thesis, dissertation , or research paper , in order to situate your work in relation to existing knowledge.

There are several reasons to conduct a literature review at the beginning of a research project:

• To familiarize yourself with the current state of knowledge on your topic
• To ensure that you’re not just repeating what others have already done
• To identify gaps in knowledge and unresolved problems that your research can address
• To develop your theoretical framework and methodology
• To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

The literature review usually comes near the beginning of your thesis or dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

A literature review is a survey of credible sources on a topic, often used in dissertations , theses, and research papers . Literature reviews give an overview of knowledge on a subject, helping you identify relevant theories and methods, as well as gaps in existing research. Literature reviews are set up similarly to other  academic texts , with an introduction , a main body, and a conclusion .

An  annotated bibliography is a list of  source references that has a short description (called an annotation ) for each of the sources. It is often assigned as part of the research process for a  paper .  

Cite this Scribbr article

If you want to cite this source, you can copy and paste the citation or click the “Cite this Scribbr article” button to automatically add the citation to our free Citation Generator.

McCombes, S. (2023, September 11). How to Write a Literature Review | Guide, Examples, & Templates. Scribbr. Retrieved April 9, 2024, from https://www.scribbr.com/dissertation/literature-review/

Is this article helpful?

Shona McCombes

Other students also liked, what is a theoretical framework | guide to organizing, what is a research methodology | steps & tips, how to write a research proposal | examples & templates, unlimited academic ai-proofreading.

✔ Document error-free in 5minutes ✔ Unlimited document corrections ✔ Specialized in correcting academic texts

Purdue Online Writing Lab Purdue OWL® College of Liberal Arts

Writing a Literature Review

Welcome to the Purdue OWL

This page is brought to you by the OWL at Purdue University. When printing this page, you must include the entire legal notice.

Copyright ©1995-2018 by The Writing Lab & The OWL at Purdue and Purdue University. All rights reserved. This material may not be published, reproduced, broadcast, rewritten, or redistributed without permission. Use of this site constitutes acceptance of our terms and conditions of fair use.

A literature review is a document or section of a document that collects key sources on a topic and discusses those sources in conversation with each other (also called synthesis ). The lit review is an important genre in many disciplines, not just literature (i.e., the study of works of literature such as novels and plays). When we say “literature review” or refer to “the literature,” we are talking about the research ( scholarship ) in a given field. You will often see the terms “the research,” “the scholarship,” and “the literature” used mostly interchangeably.

Where, when, and why would I write a lit review?

There are a number of different situations where you might write a literature review, each with slightly different expectations; different disciplines, too, have field-specific expectations for what a literature review is and does. For instance, in the humanities, authors might include more overt argumentation and interpretation of source material in their literature reviews, whereas in the sciences, authors are more likely to report study designs and results in their literature reviews; these differences reflect these disciplines’ purposes and conventions in scholarship. You should always look at examples from your own discipline and talk to professors or mentors in your field to be sure you understand your discipline’s conventions, for literature reviews as well as for any other genre.

A literature review can be a part of a research paper or scholarly article, usually falling after the introduction and before the research methods sections. In these cases, the lit review just needs to cover scholarship that is important to the issue you are writing about; sometimes it will also cover key sources that informed your research methodology.

Lit reviews can also be standalone pieces, either as assignments in a class or as publications. In a class, a lit review may be assigned to help students familiarize themselves with a topic and with scholarship in their field, get an idea of the other researchers working on the topic they’re interested in, find gaps in existing research in order to propose new projects, and/or develop a theoretical framework and methodology for later research. As a publication, a lit review usually is meant to help make other scholars’ lives easier by collecting and summarizing, synthesizing, and analyzing existing research on a topic. This can be especially helpful for students or scholars getting into a new research area, or for directing an entire community of scholars toward questions that have not yet been answered.

What are the parts of a lit review?

Most lit reviews use a basic introduction-body-conclusion structure; if your lit review is part of a larger paper, the introduction and conclusion pieces may be just a few sentences while you focus most of your attention on the body. If your lit review is a standalone piece, the introduction and conclusion take up more space and give you a place to discuss your goals, research methods, and conclusions separately from where you discuss the literature itself.

Introduction:

• An introductory paragraph that explains what your working topic and thesis is
• A forecast of key topics or texts that will appear in the review
• Potentially, a description of how you found sources and how you analyzed them for inclusion and discussion in the review (more often found in published, standalone literature reviews than in lit review sections in an article or research paper)
• Summarize and synthesize: Give an overview of the main points of each source and combine them into a coherent whole
• Analyze and interpret: Don’t just paraphrase other researchers – add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
• Critically Evaluate: Mention the strengths and weaknesses of your sources
• Write in well-structured paragraphs: Use transition words and topic sentence to draw connections, comparisons, and contrasts.

Conclusion:

• Summarize the key findings you have taken from the literature and emphasize their significance
• Connect it back to your primary research question

How should I organize my lit review?

Lit reviews can take many different organizational patterns depending on what you are trying to accomplish with the review. Here are some examples:

• Chronological : The simplest approach is to trace the development of the topic over time, which helps familiarize the audience with the topic (for instance if you are introducing something that is not commonly known in your field). If you choose this strategy, be careful to avoid simply listing and summarizing sources in order. Try to analyze the patterns, turning points, and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred (as mentioned previously, this may not be appropriate in your discipline — check with a teacher or mentor if you’re unsure).
• Thematic : If you have found some recurring central themes that you will continue working with throughout your piece, you can organize your literature review into subsections that address different aspects of the topic. For example, if you are reviewing literature about women and religion, key themes can include the role of women in churches and the religious attitude towards women.
• Qualitative versus quantitative research
• Empirical versus theoretical scholarship
• Divide the research by sociological, historical, or cultural sources
• Theoretical : In many humanities articles, the literature review is the foundation for the theoretical framework. You can use it to discuss various theories, models, and definitions of key concepts. You can argue for the relevance of a specific theoretical approach or combine various theorical concepts to create a framework for your research.

What are some strategies or tips I can use while writing my lit review?

Any lit review is only as good as the research it discusses; make sure your sources are well-chosen and your research is thorough. Don’t be afraid to do more research if you discover a new thread as you’re writing. More info on the research process is available in our "Conducting Research" resources .

As you’re doing your research, create an annotated bibliography ( see our page on the this type of document ). Much of the information used in an annotated bibliography can be used also in a literature review, so you’ll be not only partially drafting your lit review as you research, but also developing your sense of the larger conversation going on among scholars, professionals, and any other stakeholders in your topic.

Usually you will need to synthesize research rather than just summarizing it. This means drawing connections between sources to create a picture of the scholarly conversation on a topic over time. Many student writers struggle to synthesize because they feel they don’t have anything to add to the scholars they are citing; here are some strategies to help you:

• It often helps to remember that the point of these kinds of syntheses is to show your readers how you understand your research, to help them read the rest of your paper.
• Writing teachers often say synthesis is like hosting a dinner party: imagine all your sources are together in a room, discussing your topic. What are they saying to each other?
• Look at the in-text citations in each paragraph. Are you citing just one source for each paragraph? This usually indicates summary only. When you have multiple sources cited in a paragraph, you are more likely to be synthesizing them (not always, but often
• Read more about synthesis here.

The most interesting literature reviews are often written as arguments (again, as mentioned at the beginning of the page, this is discipline-specific and doesn’t work for all situations). Often, the literature review is where you can establish your research as filling a particular gap or as relevant in a particular way. You have some chance to do this in your introduction in an article, but the literature review section gives a more extended opportunity to establish the conversation in the way you would like your readers to see it. You can choose the intellectual lineage you would like to be part of and whose definitions matter most to your thinking (mostly humanities-specific, but this goes for sciences as well). In addressing these points, you argue for your place in the conversation, which tends to make the lit review more compelling than a simple reporting of other sources.

Get science-backed answers as you write with Paperpal's Research feature

What is a Literature Review? How to Write It (with Examples)

A literature review is a critical analysis and synthesis of existing research on a particular topic. It provides an overview of the current state of knowledge, identifies gaps, and highlights key findings in the literature. 1 The purpose of a literature review is to situate your own research within the context of existing scholarship, demonstrating your understanding of the topic and showing how your work contributes to the ongoing conversation in the field. Learning how to write a literature review is a critical tool for successful research. Your ability to summarize and synthesize prior research pertaining to a certain topic demonstrates your grasp on the topic of study, and assists in the learning process. 

Table of Contents

• What is the purpose of literature review? 
• a. Habitat Loss and Species Extinction: 
• b. Range Shifts and Phenological Changes: 
• c. Ocean Acidification and Coral Reefs: 
• d. Adaptive Strategies and Conservation Efforts: 
• How to write a good literature review 
• Choose a Topic and Define the Research Question: 
• Decide on the Scope of Your Review: 
• Select Databases for Searches: 
• Conduct Searches and Keep Track: 
• Review the Literature: 
• Organize and Write Your Literature Review: 
• Frequently asked questions 

What is a literature review?

A well-conducted literature review demonstrates the researcher’s familiarity with the existing literature, establishes the context for their own research, and contributes to scholarly conversations on the topic. One of the purposes of a literature review is also to help researchers avoid duplicating previous work and ensure that their research is informed by and builds upon the existing body of knowledge.

What is the purpose of literature review?

A literature review serves several important purposes within academic and research contexts. Here are some key objectives and functions of a literature review: 2  

• Contextualizing the Research Problem: The literature review provides a background and context for the research problem under investigation. It helps to situate the study within the existing body of knowledge. 
• Identifying Gaps in Knowledge: By identifying gaps, contradictions, or areas requiring further research, the researcher can shape the research question and justify the significance of the study. This is crucial for ensuring that the new research contributes something novel to the field. 
• Understanding Theoretical and Conceptual Frameworks: Literature reviews help researchers gain an understanding of the theoretical and conceptual frameworks used in previous studies. This aids in the development of a theoretical framework for the current research. 
• Providing Methodological Insights: Another purpose of literature reviews is that it allows researchers to learn about the methodologies employed in previous studies. This can help in choosing appropriate research methods for the current study and avoiding pitfalls that others may have encountered. 
• Establishing Credibility: A well-conducted literature review demonstrates the researcher’s familiarity with existing scholarship, establishing their credibility and expertise in the field. It also helps in building a solid foundation for the new research. 
• Informing Hypotheses or Research Questions: The literature review guides the formulation of hypotheses or research questions by highlighting relevant findings and areas of uncertainty in existing literature. 

Literature review example

Let’s delve deeper with a literature review example: Let’s say your literature review is about the impact of climate change on biodiversity. You might format your literature review into sections such as the effects of climate change on habitat loss and species extinction, phenological changes, and marine biodiversity. Each section would then summarize and analyze relevant studies in those areas, highlighting key findings and identifying gaps in the research. The review would conclude by emphasizing the need for further research on specific aspects of the relationship between climate change and biodiversity. The following literature review template provides a glimpse into the recommended literature review structure and content, demonstrating how research findings are organized around specific themes within a broader topic. 

Literature Review on Climate Change Impacts on Biodiversity:

Climate change is a global phenomenon with far-reaching consequences, including significant impacts on biodiversity. This literature review synthesizes key findings from various studies: 

a. Habitat Loss and Species Extinction:

Climate change-induced alterations in temperature and precipitation patterns contribute to habitat loss, affecting numerous species (Thomas et al., 2004). The review discusses how these changes increase the risk of extinction, particularly for species with specific habitat requirements. 

b. Range Shifts and Phenological Changes:

Observations of range shifts and changes in the timing of biological events (phenology) are documented in response to changing climatic conditions (Parmesan & Yohe, 2003). These shifts affect ecosystems and may lead to mismatches between species and their resources. 

c. Ocean Acidification and Coral Reefs:

The review explores the impact of climate change on marine biodiversity, emphasizing ocean acidification’s threat to coral reefs (Hoegh-Guldberg et al., 2007). Changes in pH levels negatively affect coral calcification, disrupting the delicate balance of marine ecosystems. 

d. Adaptive Strategies and Conservation Efforts:

Recognizing the urgency of the situation, the literature review discusses various adaptive strategies adopted by species and conservation efforts aimed at mitigating the impacts of climate change on biodiversity (Hannah et al., 2007). It emphasizes the importance of interdisciplinary approaches for effective conservation planning. 

How to write a good literature review

Writing a literature review involves summarizing and synthesizing existing research on a particular topic. A good literature review format should include the following elements. 

Introduction: The introduction sets the stage for your literature review, providing context and introducing the main focus of your review. 

• Opening Statement: Begin with a general statement about the broader topic and its significance in the field. 
• Scope and Purpose: Clearly define the scope of your literature review. Explain the specific research question or objective you aim to address. 
• Organizational Framework: Briefly outline the structure of your literature review, indicating how you will categorize and discuss the existing research. 
• Significance of the Study: Highlight why your literature review is important and how it contributes to the understanding of the chosen topic. 
• Thesis Statement: Conclude the introduction with a concise thesis statement that outlines the main argument or perspective you will develop in the body of the literature review. 

Body: The body of the literature review is where you provide a comprehensive analysis of existing literature, grouping studies based on themes, methodologies, or other relevant criteria. 

• Organize by Theme or Concept: Group studies that share common themes, concepts, or methodologies. Discuss each theme or concept in detail, summarizing key findings and identifying gaps or areas of disagreement. 
• Critical Analysis: Evaluate the strengths and weaknesses of each study. Discuss the methodologies used, the quality of evidence, and the overall contribution of each work to the understanding of the topic. 
• Synthesis of Findings: Synthesize the information from different studies to highlight trends, patterns, or areas of consensus in the literature. 
• Identification of Gaps: Discuss any gaps or limitations in the existing research and explain how your review contributes to filling these gaps. 
• Transition between Sections: Provide smooth transitions between different themes or concepts to maintain the flow of your literature review. 

Conclusion: The conclusion of your literature review should summarize the main findings, highlight the contributions of the review, and suggest avenues for future research. 

• Summary of Key Findings: Recap the main findings from the literature and restate how they contribute to your research question or objective. 
• Contributions to the Field: Discuss the overall contribution of your literature review to the existing knowledge in the field. 
• Implications and Applications: Explore the practical implications of the findings and suggest how they might impact future research or practice. 
• Recommendations for Future Research: Identify areas that require further investigation and propose potential directions for future research in the field. 
• Final Thoughts: Conclude with a final reflection on the importance of your literature review and its relevance to the broader academic community. 

Conducting a literature review

Conducting a literature review is an essential step in research that involves reviewing and analyzing existing literature on a specific topic. It’s important to know how to do a literature review effectively, so here are the steps to follow: 1  

Choose a Topic and Define the Research Question:

• Select a topic that is relevant to your field of study. 
• Clearly define your research question or objective. Determine what specific aspect of the topic do you want to explore? 

Decide on the Scope of Your Review:

• Determine the timeframe for your literature review. Are you focusing on recent developments, or do you want a historical overview? 
• Consider the geographical scope. Is your review global, or are you focusing on a specific region? 
• Define the inclusion and exclusion criteria. What types of sources will you include? Are there specific types of studies or publications you will exclude? 

Select Databases for Searches:

• Identify relevant databases for your field. Examples include PubMed, IEEE Xplore, Scopus, Web of Science, and Google Scholar. 
• Consider searching in library catalogs, institutional repositories, and specialized databases related to your topic. 

Conduct Searches and Keep Track:

• Develop a systematic search strategy using keywords, Boolean operators (AND, OR, NOT), and other search techniques. 
• Record and document your search strategy for transparency and replicability. 
• Keep track of the articles, including publication details, abstracts, and links. Use citation management tools like EndNote, Zotero, or Mendeley to organize your references. 

Review the Literature:

• Evaluate the relevance and quality of each source. Consider the methodology, sample size, and results of studies. 
• Organize the literature by themes or key concepts. Identify patterns, trends, and gaps in the existing research. 
• Summarize key findings and arguments from each source. Compare and contrast different perspectives. 
• Identify areas where there is a consensus in the literature and where there are conflicting opinions. 
• Provide critical analysis and synthesis of the literature. What are the strengths and weaknesses of existing research? 

Organize and Write Your Literature Review:

• Literature review outline should be based on themes, chronological order, or methodological approaches. 
• Write a clear and coherent narrative that synthesizes the information gathered. 
• Use proper citations for each source and ensure consistency in your citation style (APA, MLA, Chicago, etc.). 
• Conclude your literature review by summarizing key findings, identifying gaps, and suggesting areas for future research. 

The literature review sample and detailed advice on writing and conducting a review will help you produce a well-structured report. But remember that a literature review is an ongoing process, and it may be necessary to revisit and update it as your research progresses. 

Frequently asked questions

A literature review is a critical and comprehensive analysis of existing literature (published and unpublished works) on a specific topic or research question and provides a synthesis of the current state of knowledge in a particular field. A well-conducted literature review is crucial for researchers to build upon existing knowledge, avoid duplication of efforts, and contribute to the advancement of their field. It also helps researchers situate their work within a broader context and facilitates the development of a sound theoretical and conceptual framework for their studies.

Literature review is a crucial component of research writing, providing a solid background for a research paper’s investigation. The aim is to keep professionals up to date by providing an understanding of ongoing developments within a specific field, including research methods, and experimental techniques used in that field, and present that knowledge in the form of a written report. Also, the depth and breadth of the literature review emphasizes the credibility of the scholar in his or her field.  

Before writing a literature review, it’s essential to undertake several preparatory steps to ensure that your review is well-researched, organized, and focused. This includes choosing a topic of general interest to you and doing exploratory research on that topic, writing an annotated bibliography, and noting major points, especially those that relate to the position you have taken on the topic. 

Literature reviews and academic research papers are essential components of scholarly work but serve different purposes within the academic realm. 3 A literature review aims to provide a foundation for understanding the current state of research on a particular topic, identify gaps or controversies, and lay the groundwork for future research. Therefore, it draws heavily from existing academic sources, including books, journal articles, and other scholarly publications. In contrast, an academic research paper aims to present new knowledge, contribute to the academic discourse, and advance the understanding of a specific research question. Therefore, it involves a mix of existing literature (in the introduction and literature review sections) and original data or findings obtained through research methods. 

Literature reviews are essential components of academic and research papers, and various strategies can be employed to conduct them effectively. If you want to know how to write a literature review for a research paper, here are four common approaches that are often used by researchers.  Chronological Review: This strategy involves organizing the literature based on the chronological order of publication. It helps to trace the development of a topic over time, showing how ideas, theories, and research have evolved.  Thematic Review: Thematic reviews focus on identifying and analyzing themes or topics that cut across different studies. Instead of organizing the literature chronologically, it is grouped by key themes or concepts, allowing for a comprehensive exploration of various aspects of the topic.  Methodological Review: This strategy involves organizing the literature based on the research methods employed in different studies. It helps to highlight the strengths and weaknesses of various methodologies and allows the reader to evaluate the reliability and validity of the research findings.  Theoretical Review: A theoretical review examines the literature based on the theoretical frameworks used in different studies. This approach helps to identify the key theories that have been applied to the topic and assess their contributions to the understanding of the subject.  It’s important to note that these strategies are not mutually exclusive, and a literature review may combine elements of more than one approach. The choice of strategy depends on the research question, the nature of the literature available, and the goals of the review. Additionally, other strategies, such as integrative reviews or systematic reviews, may be employed depending on the specific requirements of the research.

The literature review format can vary depending on the specific publication guidelines. However, there are some common elements and structures that are often followed. Here is a general guideline for the format of a literature review:  Introduction:   Provide an overview of the topic.  Define the scope and purpose of the literature review.  State the research question or objective.  Body:   Organize the literature by themes, concepts, or chronology.  Critically analyze and evaluate each source.  Discuss the strengths and weaknesses of the studies.  Highlight any methodological limitations or biases.  Identify patterns, connections, or contradictions in the existing research.  Conclusion:   Summarize the key points discussed in the literature review.  Highlight the research gap.  Address the research question or objective stated in the introduction.  Highlight the contributions of the review and suggest directions for future research.

Both annotated bibliographies and literature reviews involve the examination of scholarly sources. While annotated bibliographies focus on individual sources with brief annotations, literature reviews provide a more in-depth, integrated, and comprehensive analysis of existing literature on a specific topic. The key differences are as follows: 

References 

• Denney, A. S., & Tewksbury, R. (2013). How to write a literature review.  Journal of criminal justice education ,  24 (2), 218-234. 
• Pan, M. L. (2016).  Preparing literature reviews: Qualitative and quantitative approaches . Taylor & Francis. 
• Cantero, C. (2019). How to write a literature review.  San José State University Writing Center . 

Paperpal is an AI writing assistant that help academics write better, faster with real-time suggestions for in-depth language and grammar correction. Trained on millions of research manuscripts enhanced by professional academic editors, Paperpal delivers human precision at machine speed.  

Try it for free or upgrade to  Paperpal Prime , which unlocks unlimited access to premium features like academic translation, paraphrasing, contextual synonyms, consistency checks and more. It’s like always having a professional academic editor by your side! Go beyond limitations and experience the future of academic writing.  Get Paperpal Prime now at just US$19 a month!

Related Reads:

• Empirical Research: A Comprehensive Guide for Academics 
• How to Write a Scientific Paper in 10 Steps 
• Life Sciences Papers: 9 Tips for Authors Writing in Biological Sciences
• What is an Argumentative Essay? How to Write It (With Examples)

6 Tips for Post-Doc Researchers to Take Their Career to the Next Level

Self-plagiarism in research: what it is and how to avoid it, you may also like, what is hedging in academic writing  , how to use ai to enhance your college..., ai + human expertise – a paradigm shift..., how to use paperpal to generate emails &..., ai in education: it’s time to change the..., is it ethical to use ai-generated abstracts without..., do plagiarism checkers detect ai content, word choice problems: how to use the right..., how to avoid plagiarism when using generative ai..., what are journal guidelines on using generative ai....

• University of Texas Libraries

Literature Reviews

• What is a literature review?
• Steps in the Literature Review Process
• Define your research question
• Determine inclusion and exclusion criteria
• Choose databases and search
• Review Results
• Synthesize Results
• Analyze Results
• Librarian Support

What is a Literature Review?

A literature or narrative review is a comprehensive review and analysis of the published literature on a specific topic or research question. The literature that is reviewed contains: books, articles, academic articles, conference proceedings, association papers, and dissertations. It contains the most pertinent studies and points to important past and current research and practices. It provides background and context, and shows how your research will contribute to the field. 

A literature review should: 

• Provide a comprehensive and updated review of the literature;
• Explain why this review has taken place;
• Articulate a position or hypothesis;
• Acknowledge and account for conflicting and corroborating points of view

From  S age Research Methods

Purpose of a Literature Review

A literature review can be written as an introduction to a study to:

• Demonstrate how a study fills a gap in research
• Compare a study with other research that's been done

Or it can be a separate work (a research article on its own) which:

• Organizes or describes a topic
• Describes variables within a particular issue/problem

Limitations of a Literature Review

Some of the limitations of a literature review are:

• It's a snapshot in time. Unlike other reviews, this one has beginning, a middle and an end. There may be future developments that could make your work less relevant.
• It may be too focused. Some niche studies may miss the bigger picture.
• It can be difficult to be comprehensive. There is no way to make sure all the literature on a topic was considered.
• It is easy to be biased if you stick to top tier journals. There may be other places where people are publishing exemplary research. Look to open access publications and conferences to reflect a more inclusive collection. Also, make sure to include opposing views (and not just supporting evidence).

Source: Grant, Maria J., and Andrew Booth. “A Typology of Reviews: An Analysis of 14 Review Types and Associated Methodologies.” Health Information & Libraries Journal, vol. 26, no. 2, June 2009, pp. 91–108. Wiley Online Library, doi:10.1111/j.1471-1842.2009.00848.x.

Meryl Brodsky : Communication and Information Studies

Hannah Chapman Tripp : Biology, Neuroscience

Carolyn Cunningham : Human Development & Family Sciences, Psychology, Sociology

Larayne Dallas : Engineering

Janelle Hedstrom : Special Education, Curriculum & Instruction, Ed Leadership & Policy ​

Susan Macicak : Linguistics

Imelda Vetter : Dell Medical School

For help in other subject areas, please see the guide to library specialists by subject .

Periodically, UT Libraries runs a workshop covering the basics and library support for literature reviews. While we try to offer these once per academic year, we find providing the recording to be helpful to community members who have missed the session. Following is the most recent recording of the workshop, Conducting a Literature Review. To view the recording, a UT login is required.

• October 26, 2022 recording
• Last Updated: Oct 26, 2022 2:49 PM
• URL: https://guides.lib.utexas.edu/literaturereviews

Have a language expert improve your writing

Run a free plagiarism check in 10 minutes, automatically generate references for free.

• Knowledge Base
• Dissertation
• What is a Literature Review? | Guide, Template, & Examples

What is a Literature Review? | Guide, Template, & Examples

Published on 22 February 2022 by Shona McCombes . Revised on 7 June 2022.

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research.

There are five key steps to writing a literature review:

• Search for relevant literature
• Evaluate sources
• Identify themes, debates and gaps
• Outline the structure
• Write your literature review

A good literature review doesn’t just summarise sources – it analyses, synthesises, and critically evaluates to give a clear picture of the state of knowledge on the subject.

Instantly correct all language mistakes in your text

Be assured that you'll submit flawless writing. Upload your document to correct all your mistakes.

Table of contents

Why write a literature review, examples of literature reviews, step 1: search for relevant literature, step 2: evaluate and select sources, step 3: identify themes, debates and gaps, step 4: outline your literature review’s structure, step 5: write your literature review, frequently asked questions about literature reviews, introduction.

• Quick Run-through
• Step 1 & 2

When you write a dissertation or thesis, you will have to conduct a literature review to situate your research within existing knowledge. The literature review gives you a chance to:

• Demonstrate your familiarity with the topic and scholarly context
• Develop a theoretical framework and methodology for your research
• Position yourself in relation to other researchers and theorists
• Show how your dissertation addresses a gap or contributes to a debate

You might also have to write a literature review as a stand-alone assignment. In this case, the purpose is to evaluate the current state of research and demonstrate your knowledge of scholarly debates around a topic.

The content will look slightly different in each case, but the process of conducting a literature review follows the same steps. We’ve written a step-by-step guide that you can follow below.

The only proofreading tool specialized in correcting academic writing

The academic proofreading tool has been trained on 1000s of academic texts and by native English editors. Making it the most accurate and reliable proofreading tool for students.

Correct my document today

Writing literature reviews can be quite challenging! A good starting point could be to look at some examples, depending on what kind of literature review you’d like to write.

• Example literature review #1: “Why Do People Migrate? A Review of the Theoretical Literature” ( Theoretical literature review about the development of economic migration theory from the 1950s to today.)
• Example literature review #2: “Literature review as a research methodology: An overview and guidelines” ( Methodological literature review about interdisciplinary knowledge acquisition and production.)
• Example literature review #3: “The Use of Technology in English Language Learning: A Literature Review” ( Thematic literature review about the effects of technology on language acquisition.)
• Example literature review #4: “Learners’ Listening Comprehension Difficulties in English Language Learning: A Literature Review” ( Chronological literature review about how the concept of listening skills has changed over time.)

You can also check out our templates with literature review examples and sample outlines at the links below.

Download Word doc Download Google doc

Before you begin searching for literature, you need a clearly defined topic .

If you are writing the literature review section of a dissertation or research paper, you will search for literature related to your research objectives and questions .

If you are writing a literature review as a stand-alone assignment, you will have to choose a focus and develop a central question to direct your search. Unlike a dissertation research question, this question has to be answerable without collecting original data. You should be able to answer it based only on a review of existing publications.

Make a list of keywords

Start by creating a list of keywords related to your research topic. Include each of the key concepts or variables you’re interested in, and list any synonyms and related terms. You can add to this list if you discover new keywords in the process of your literature search.

• Social media, Facebook, Instagram, Twitter, Snapchat, TikTok
• Body image, self-perception, self-esteem, mental health
• Generation Z, teenagers, adolescents, youth

Search for relevant sources

Use your keywords to begin searching for sources. Some databases to search for journals and articles include:

• Your university’s library catalogue
• Google Scholar
• Project Muse (humanities and social sciences)
• Medline (life sciences and biomedicine)
• EconLit (economics)
• Inspec (physics, engineering and computer science)

You can use boolean operators to help narrow down your search:

Read the abstract to find out whether an article is relevant to your question. When you find a useful book or article, you can check the bibliography to find other relevant sources.

To identify the most important publications on your topic, take note of recurring citations. If the same authors, books or articles keep appearing in your reading, make sure to seek them out.

You probably won’t be able to read absolutely everything that has been written on the topic – you’ll have to evaluate which sources are most relevant to your questions.

For each publication, ask yourself:

• What question or problem is the author addressing?
• What are the key concepts and how are they defined?
• What are the key theories, models and methods? Does the research use established frameworks or take an innovative approach?
• What are the results and conclusions of the study?
• How does the publication relate to other literature in the field? Does it confirm, add to, or challenge established knowledge?
• How does the publication contribute to your understanding of the topic? What are its key insights and arguments?
• What are the strengths and weaknesses of the research?

Make sure the sources you use are credible, and make sure you read any landmark studies and major theories in your field of research.

You can find out how many times an article has been cited on Google Scholar – a high citation count means the article has been influential in the field, and should certainly be included in your literature review.

The scope of your review will depend on your topic and discipline: in the sciences you usually only review recent literature, but in the humanities you might take a long historical perspective (for example, to trace how a concept has changed in meaning over time).

Remember that you can use our template to summarise and evaluate sources you’re thinking about using!

Take notes and cite your sources

As you read, you should also begin the writing process. Take notes that you can later incorporate into the text of your literature review.

It’s important to keep track of your sources with references to avoid plagiarism . It can be helpful to make an annotated bibliography, where you compile full reference information and write a paragraph of summary and analysis for each source. This helps you remember what you read and saves time later in the process.

You can use our free APA Reference Generator for quick, correct, consistent citations.

To begin organising your literature review’s argument and structure, you need to understand the connections and relationships between the sources you’ve read. Based on your reading and notes, you can look for:

• Trends and patterns (in theory, method or results): do certain approaches become more or less popular over time?
• Themes: what questions or concepts recur across the literature?
• Debates, conflicts and contradictions: where do sources disagree?
• Pivotal publications: are there any influential theories or studies that changed the direction of the field?
• Gaps: what is missing from the literature? Are there weaknesses that need to be addressed?

This step will help you work out the structure of your literature review and (if applicable) show how your own research will contribute to existing knowledge.

• Most research has focused on young women.
• There is an increasing interest in the visual aspects of social media.
• But there is still a lack of robust research on highly-visual platforms like Instagram and Snapchat – this is a gap that you could address in your own research.

There are various approaches to organising the body of a literature review. You should have a rough idea of your strategy before you start writing.

Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

The simplest approach is to trace the development of the topic over time. However, if you choose this strategy, be careful to avoid simply listing and summarising sources in order.

Try to analyse patterns, turning points and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred.

If you have found some recurring central themes, you can organise your literature review into subsections that address different aspects of the topic.

For example, if you are reviewing literature about inequalities in migrant health outcomes, key themes might include healthcare policy, language barriers, cultural attitudes, legal status, and economic access.

Methodological

If you draw your sources from different disciplines or fields that use a variety of research methods , you might want to compare the results and conclusions that emerge from different approaches. For example:

• Look at what results have emerged in qualitative versus quantitative research
• Discuss how the topic has been approached by empirical versus theoretical scholarship
• Divide the literature into sociological, historical, and cultural sources

Theoretical

A literature review is often the foundation for a theoretical framework . You can use it to discuss various theories, models, and definitions of key concepts.

You might argue for the relevance of a specific theoretical approach, or combine various theoretical concepts to create a framework for your research.

Like any other academic text, your literature review should have an introduction , a main body, and a conclusion . What you include in each depends on the objective of your literature review.

The introduction should clearly establish the focus and purpose of the literature review.

If you are writing the literature review as part of your dissertation or thesis, reiterate your central problem or research question and give a brief summary of the scholarly context. You can emphasise the timeliness of the topic (“many recent studies have focused on the problem of x”) or highlight a gap in the literature (“while there has been much research on x, few researchers have taken y into consideration”).

Depending on the length of your literature review, you might want to divide the body into subsections. You can use a subheading for each theme, time period, or methodological approach.

As you write, make sure to follow these tips:

• Summarise and synthesise: give an overview of the main points of each source and combine them into a coherent whole.
• Analyse and interpret: don’t just paraphrase other researchers – add your own interpretations, discussing the significance of findings in relation to the literature as a whole.
• Critically evaluate: mention the strengths and weaknesses of your sources.
• Write in well-structured paragraphs: use transitions and topic sentences to draw connections, comparisons and contrasts.

In the conclusion, you should summarise the key findings you have taken from the literature and emphasise their significance.

If the literature review is part of your dissertation or thesis, reiterate how your research addresses gaps and contributes new knowledge, or discuss how you have drawn on existing theories and methods to build a framework for your research. This can lead directly into your methodology section.

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a dissertation , thesis, research paper , or proposal .

There are several reasons to conduct a literature review at the beginning of a research project:

• To familiarise yourself with the current state of knowledge on your topic
• To ensure that you’re not just repeating what others have already done
• To identify gaps in knowledge and unresolved problems that your research can address
• To develop your theoretical framework and methodology
• To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

The literature review usually comes near the beginning of your  dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

Cite this Scribbr article

If you want to cite this source, you can copy and paste the citation or click the ‘Cite this Scribbr article’ button to automatically add the citation to our free Reference Generator.

McCombes, S. (2022, June 07). What is a Literature Review? | Guide, Template, & Examples. Scribbr. Retrieved 9 April 2024, from https://www.scribbr.co.uk/thesis-dissertation/literature-review/

Is this article helpful?

Shona McCombes

Other students also liked, how to write a dissertation proposal | a step-by-step guide, what is a theoretical framework | a step-by-step guide, what is a research methodology | steps & tips.

Reference management. Clean and simple.

What is a literature review? [with examples]

What is a literature review?

The purpose of a literature review, how to write a literature review, the format of a literature review, general formatting rules, the length of a literature review, literature review examples, frequently asked questions about literature reviews, related articles.

A literature review is an assessment of the sources in a chosen topic of research.

In a literature review, you’re expected to report on the existing scholarly conversation, without adding new contributions.

If you are currently writing one, you've come to the right place. In the following paragraphs, we will explain:

• the objective of a literature review
• how to write a literature review
• the basic format of a literature review

Tip: It’s not always mandatory to add a literature review in a paper. Theses and dissertations often include them, whereas research papers may not. Make sure to consult with your instructor for exact requirements.

The four main objectives of a literature review are:

• Studying the references of your research area
• Summarizing the main arguments
• Identifying current gaps, stances, and issues
• Presenting all of the above in a text

Ultimately, the main goal of a literature review is to provide the researcher with sufficient knowledge about the topic in question so that they can eventually make an intervention.

The format of a literature review is fairly standard. It includes an:

• introduction that briefly introduces the main topic
• body that includes the main discussion of the key arguments
• conclusion that highlights the gaps and issues of the literature

➡️ Take a look at our guide on how to write a literature review to learn more about how to structure a literature review.

First of all, a literature review should have its own labeled section. You should indicate clearly in the table of contents where the literature can be found, and you should label this section as “Literature Review.”

➡️ For more information on writing a thesis, visit our guide on how to structure a thesis .

There is no set amount of words for a literature review, so the length depends on the research. If you are working with a large amount of sources, it will be long. If your paper does not depend entirely on references, it will be short.

Take a look at these three theses featuring great literature reviews:

• School-Based Speech-Language Pathologist's Perceptions of Sensory Food Aversions in Children [ PDF , see page 20]
• Who's Writing What We Read: Authorship in Criminological Research [ PDF , see page 4]
• A Phenomenological Study of the Lived Experience of Online Instructors of Theological Reflection at Christian Institutions Accredited by the Association of Theological Schools [ PDF , see page 56]

Literature reviews are most commonly found in theses and dissertations. However, you find them in research papers as well.

There is no set amount of words for a literature review, so the length depends on the research. If you are working with a large amount of sources, then it will be long. If your paper does not depend entirely on references, then it will be short.

No. A literature review should have its own independent section. You should indicate clearly in the table of contents where the literature review can be found, and label this section as “Literature Review.”

The main goal of a literature review is to provide the researcher with sufficient knowledge about the topic in question so that they can eventually make an intervention.

Literature Reviews

What this handout is about.

This handout will explain what literature reviews are and offer insights into the form and construction of literature reviews in the humanities, social sciences, and sciences.

Introduction

OK. You’ve got to write a literature review. You dust off a novel and a book of poetry, settle down in your chair, and get ready to issue a “thumbs up” or “thumbs down” as you leaf through the pages. “Literature review” done. Right?

Wrong! The “literature” of a literature review refers to any collection of materials on a topic, not necessarily the great literary texts of the world. “Literature” could be anything from a set of government pamphlets on British colonial methods in Africa to scholarly articles on the treatment of a torn ACL. And a review does not necessarily mean that your reader wants you to give your personal opinion on whether or not you liked these sources.

What is a literature review, then?

A literature review discusses published information in a particular subject area, and sometimes information in a particular subject area within a certain time period.

A literature review can be just a simple summary of the sources, but it usually has an organizational pattern and combines both summary and synthesis. A summary is a recap of the important information of the source, but a synthesis is a re-organization, or a reshuffling, of that information. It might give a new interpretation of old material or combine new with old interpretations. Or it might trace the intellectual progression of the field, including major debates. And depending on the situation, the literature review may evaluate the sources and advise the reader on the most pertinent or relevant.

But how is a literature review different from an academic research paper?

The main focus of an academic research paper is to develop a new argument, and a research paper is likely to contain a literature review as one of its parts. In a research paper, you use the literature as a foundation and as support for a new insight that you contribute. The focus of a literature review, however, is to summarize and synthesize the arguments and ideas of others without adding new contributions.

Why do we write literature reviews?

Literature reviews provide you with a handy guide to a particular topic. If you have limited time to conduct research, literature reviews can give you an overview or act as a stepping stone. For professionals, they are useful reports that keep them up to date with what is current in the field. For scholars, the depth and breadth of the literature review emphasizes the credibility of the writer in his or her field. Literature reviews also provide a solid background for a research paper’s investigation. Comprehensive knowledge of the literature of the field is essential to most research papers.

Who writes these things, anyway?

Literature reviews are written occasionally in the humanities, but mostly in the sciences and social sciences; in experiment and lab reports, they constitute a section of the paper. Sometimes a literature review is written as a paper in itself.

Let’s get to it! What should I do before writing the literature review?

If your assignment is not very specific, seek clarification from your instructor:

• Roughly how many sources should you include?
• What types of sources (books, journal articles, websites)?
• Should you summarize, synthesize, or critique your sources by discussing a common theme or issue?
• Should you evaluate your sources?
• Should you provide subheadings and other background information, such as definitions and/or a history?

Find models

Look for other literature reviews in your area of interest or in the discipline and read them to get a sense of the types of themes you might want to look for in your own research or ways to organize your final review. You can simply put the word “review” in your search engine along with your other topic terms to find articles of this type on the Internet or in an electronic database. The bibliography or reference section of sources you’ve already read are also excellent entry points into your own research.

Narrow your topic

There are hundreds or even thousands of articles and books on most areas of study. The narrower your topic, the easier it will be to limit the number of sources you need to read in order to get a good survey of the material. Your instructor will probably not expect you to read everything that’s out there on the topic, but you’ll make your job easier if you first limit your scope.

Keep in mind that UNC Libraries have research guides and to databases relevant to many fields of study. You can reach out to the subject librarian for a consultation: https://library.unc.edu/support/consultations/ .

And don’t forget to tap into your professor’s (or other professors’) knowledge in the field. Ask your professor questions such as: “If you had to read only one book from the 90’s on topic X, what would it be?” Questions such as this help you to find and determine quickly the most seminal pieces in the field.

Consider whether your sources are current

Some disciplines require that you use information that is as current as possible. In the sciences, for instance, treatments for medical problems are constantly changing according to the latest studies. Information even two years old could be obsolete. However, if you are writing a review in the humanities, history, or social sciences, a survey of the history of the literature may be what is needed, because what is important is how perspectives have changed through the years or within a certain time period. Try sorting through some other current bibliographies or literature reviews in the field to get a sense of what your discipline expects. You can also use this method to consider what is currently of interest to scholars in this field and what is not.

Strategies for writing the literature review

Find a focus.

A literature review, like a term paper, is usually organized around ideas, not the sources themselves as an annotated bibliography would be organized. This means that you will not just simply list your sources and go into detail about each one of them, one at a time. No. As you read widely but selectively in your topic area, consider instead what themes or issues connect your sources together. Do they present one or different solutions? Is there an aspect of the field that is missing? How well do they present the material and do they portray it according to an appropriate theory? Do they reveal a trend in the field? A raging debate? Pick one of these themes to focus the organization of your review.

Convey it to your reader

A literature review may not have a traditional thesis statement (one that makes an argument), but you do need to tell readers what to expect. Try writing a simple statement that lets the reader know what is your main organizing principle. Here are a couple of examples:

The current trend in treatment for congestive heart failure combines surgery and medicine. More and more cultural studies scholars are accepting popular media as a subject worthy of academic consideration.

Consider organization

You’ve got a focus, and you’ve stated it clearly and directly. Now what is the most effective way of presenting the information? What are the most important topics, subtopics, etc., that your review needs to include? And in what order should you present them? Develop an organization for your review at both a global and local level:

First, cover the basic categories

Just like most academic papers, literature reviews also must contain at least three basic elements: an introduction or background information section; the body of the review containing the discussion of sources; and, finally, a conclusion and/or recommendations section to end the paper. The following provides a brief description of the content of each:

• Introduction: Gives a quick idea of the topic of the literature review, such as the central theme or organizational pattern.
• Body: Contains your discussion of sources and is organized either chronologically, thematically, or methodologically (see below for more information on each).
• Conclusions/Recommendations: Discuss what you have drawn from reviewing literature so far. Where might the discussion proceed?

Organizing the body

Once you have the basic categories in place, then you must consider how you will present the sources themselves within the body of your paper. Create an organizational method to focus this section even further.

To help you come up with an overall organizational framework for your review, consider the following scenario:

You’ve decided to focus your literature review on materials dealing with sperm whales. This is because you’ve just finished reading Moby Dick, and you wonder if that whale’s portrayal is really real. You start with some articles about the physiology of sperm whales in biology journals written in the 1980’s. But these articles refer to some British biological studies performed on whales in the early 18th century. So you check those out. Then you look up a book written in 1968 with information on how sperm whales have been portrayed in other forms of art, such as in Alaskan poetry, in French painting, or on whale bone, as the whale hunters in the late 19th century used to do. This makes you wonder about American whaling methods during the time portrayed in Moby Dick, so you find some academic articles published in the last five years on how accurately Herman Melville portrayed the whaling scene in his novel.

Now consider some typical ways of organizing the sources into a review:

• Chronological: If your review follows the chronological method, you could write about the materials above according to when they were published. For instance, first you would talk about the British biological studies of the 18th century, then about Moby Dick, published in 1851, then the book on sperm whales in other art (1968), and finally the biology articles (1980s) and the recent articles on American whaling of the 19th century. But there is relatively no continuity among subjects here. And notice that even though the sources on sperm whales in other art and on American whaling are written recently, they are about other subjects/objects that were created much earlier. Thus, the review loses its chronological focus.
• By publication: Order your sources by publication chronology, then, only if the order demonstrates a more important trend. For instance, you could order a review of literature on biological studies of sperm whales if the progression revealed a change in dissection practices of the researchers who wrote and/or conducted the studies.
• By trend: A better way to organize the above sources chronologically is to examine the sources under another trend, such as the history of whaling. Then your review would have subsections according to eras within this period. For instance, the review might examine whaling from pre-1600-1699, 1700-1799, and 1800-1899. Under this method, you would combine the recent studies on American whaling in the 19th century with Moby Dick itself in the 1800-1899 category, even though the authors wrote a century apart.
• Thematic: Thematic reviews of literature are organized around a topic or issue, rather than the progression of time. However, progression of time may still be an important factor in a thematic review. For instance, the sperm whale review could focus on the development of the harpoon for whale hunting. While the study focuses on one topic, harpoon technology, it will still be organized chronologically. The only difference here between a “chronological” and a “thematic” approach is what is emphasized the most: the development of the harpoon or the harpoon technology.But more authentic thematic reviews tend to break away from chronological order. For instance, a thematic review of material on sperm whales might examine how they are portrayed as “evil” in cultural documents. The subsections might include how they are personified, how their proportions are exaggerated, and their behaviors misunderstood. A review organized in this manner would shift between time periods within each section according to the point made.
• Methodological: A methodological approach differs from the two above in that the focusing factor usually does not have to do with the content of the material. Instead, it focuses on the “methods” of the researcher or writer. For the sperm whale project, one methodological approach would be to look at cultural differences between the portrayal of whales in American, British, and French art work. Or the review might focus on the economic impact of whaling on a community. A methodological scope will influence either the types of documents in the review or the way in which these documents are discussed. Once you’ve decided on the organizational method for the body of the review, the sections you need to include in the paper should be easy to figure out. They should arise out of your organizational strategy. In other words, a chronological review would have subsections for each vital time period. A thematic review would have subtopics based upon factors that relate to the theme or issue.

Sometimes, though, you might need to add additional sections that are necessary for your study, but do not fit in the organizational strategy of the body. What other sections you include in the body is up to you. Put in only what is necessary. Here are a few other sections you might want to consider:

• Current Situation: Information necessary to understand the topic or focus of the literature review.
• History: The chronological progression of the field, the literature, or an idea that is necessary to understand the literature review, if the body of the literature review is not already a chronology.
• Methods and/or Standards: The criteria you used to select the sources in your literature review or the way in which you present your information. For instance, you might explain that your review includes only peer-reviewed articles and journals.

Questions for Further Research: What questions about the field has the review sparked? How will you further your research as a result of the review?

Begin composing

Once you’ve settled on a general pattern of organization, you’re ready to write each section. There are a few guidelines you should follow during the writing stage as well. Here is a sample paragraph from a literature review about sexism and language to illuminate the following discussion:

However, other studies have shown that even gender-neutral antecedents are more likely to produce masculine images than feminine ones (Gastil, 1990). Hamilton (1988) asked students to complete sentences that required them to fill in pronouns that agreed with gender-neutral antecedents such as “writer,” “pedestrian,” and “persons.” The students were asked to describe any image they had when writing the sentence. Hamilton found that people imagined 3.3 men to each woman in the masculine “generic” condition and 1.5 men per woman in the unbiased condition. Thus, while ambient sexism accounted for some of the masculine bias, sexist language amplified the effect. (Source: Erika Falk and Jordan Mills, “Why Sexist Language Affects Persuasion: The Role of Homophily, Intended Audience, and Offense,” Women and Language19:2).

Use evidence

In the example above, the writers refer to several other sources when making their point. A literature review in this sense is just like any other academic research paper. Your interpretation of the available sources must be backed up with evidence to show that what you are saying is valid.

Be selective

Select only the most important points in each source to highlight in the review. The type of information you choose to mention should relate directly to the review’s focus, whether it is thematic, methodological, or chronological.

Use quotes sparingly

Falk and Mills do not use any direct quotes. That is because the survey nature of the literature review does not allow for in-depth discussion or detailed quotes from the text. Some short quotes here and there are okay, though, if you want to emphasize a point, or if what the author said just cannot be rewritten in your own words. Notice that Falk and Mills do quote certain terms that were coined by the author, not common knowledge, or taken directly from the study. But if you find yourself wanting to put in more quotes, check with your instructor.

Summarize and synthesize

Remember to summarize and synthesize your sources within each paragraph as well as throughout the review. The authors here recapitulate important features of Hamilton’s study, but then synthesize it by rephrasing the study’s significance and relating it to their own work.

Keep your own voice

While the literature review presents others’ ideas, your voice (the writer’s) should remain front and center. Notice that Falk and Mills weave references to other sources into their own text, but they still maintain their own voice by starting and ending the paragraph with their own ideas and their own words. The sources support what Falk and Mills are saying.

Use caution when paraphrasing

When paraphrasing a source that is not your own, be sure to represent the author’s information or opinions accurately and in your own words. In the preceding example, Falk and Mills either directly refer in the text to the author of their source, such as Hamilton, or they provide ample notation in the text when the ideas they are mentioning are not their own, for example, Gastil’s. For more information, please see our handout on plagiarism .

Revise, revise, revise

Draft in hand? Now you’re ready to revise. Spending a lot of time revising is a wise idea, because your main objective is to present the material, not the argument. So check over your review again to make sure it follows the assignment and/or your outline. Then, just as you would for most other academic forms of writing, rewrite or rework the language of your review so that you’ve presented your information in the most concise manner possible. Be sure to use terminology familiar to your audience; get rid of unnecessary jargon or slang. Finally, double check that you’ve documented your sources and formatted the review appropriately for your discipline. For tips on the revising and editing process, see our handout on revising drafts .

Works consulted

We consulted these works while writing this handout. This is not a comprehensive list of resources on the handout’s topic, and we encourage you to do your own research to find additional publications. Please do not use this list as a model for the format of your own reference list, as it may not match the citation style you are using. For guidance on formatting citations, please see the UNC Libraries citation tutorial . We revise these tips periodically and welcome feedback.

Anson, Chris M., and Robert A. Schwegler. 2010. The Longman Handbook for Writers and Readers , 6th ed. New York: Longman.

Jones, Robert, Patrick Bizzaro, and Cynthia Selfe. 1997. The Harcourt Brace Guide to Writing in the Disciplines . New York: Harcourt Brace.

Lamb, Sandra E. 1998. How to Write It: A Complete Guide to Everything You’ll Ever Write . Berkeley: Ten Speed Press.

Rosen, Leonard J., and Laurence Behrens. 2003. The Allyn & Bacon Handbook , 5th ed. New York: Longman.

Troyka, Lynn Quittman, and Doug Hesse. 2016. Simon and Schuster Handbook for Writers , 11th ed. London: Pearson.

You may reproduce it for non-commercial use if you use the entire handout and attribute the source: The Writing Center, University of North Carolina at Chapel Hill

Make a Gift

• UConn Library
• Literature Review: The What, Why and How-to Guide
• Introduction

Literature Review: The What, Why and How-to Guide — Introduction

• Getting Started
• How to Pick a Topic
• Strategies to Find Sources
• Evaluating Sources & Lit. Reviews
• Tips for Writing Literature Reviews
• Writing Literature Review: Useful Sites
• Citation Resources
• Other Academic Writings

What are Literature Reviews?

So, what is a literature review? "A literature review is an account of what has been published on a topic by accredited scholars and researchers. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available, or a set of summaries." Taylor, D.  The literature review: A few tips on conducting it . University of Toronto Health Sciences Writing Centre.

Goals of Literature Reviews

What are the goals of creating a Literature Review?  A literature could be written to accomplish different aims:

• To develop a theory or evaluate an existing theory
• To summarize the historical or existing state of a research topic
• Identify a problem in a field of research 

Baumeister, R. F., & Leary, M. R. (1997). Writing narrative literature reviews .  Review of General Psychology , 1 (3), 311-320.

What kinds of sources require a Literature Review?

• A research paper assigned in a course
• A thesis or dissertation
• A grant proposal
• An article intended for publication in a journal

All these instances require you to collect what has been written about your research topic so that you can demonstrate how your own research sheds new light on the topic.

Types of Literature Reviews

What kinds of literature reviews are written?

Narrative review: The purpose of this type of review is to describe the current state of the research on a specific topic/research and to offer a critical analysis of the literature reviewed. Studies are grouped by research/theoretical categories, and themes and trends, strengths and weakness, and gaps are identified. The review ends with a conclusion section which summarizes the findings regarding the state of the research of the specific study, the gaps identify and if applicable, explains how the author's research will address gaps identify in the review and expand the knowledge on the topic reviewed.

• Example : Predictors and Outcomes of U.S. Quality Maternity Leave: A Review and Conceptual Framework:  10.1177/08948453211037398  

Systematic review : "The authors of a systematic review use a specific procedure to search the research literature, select the studies to include in their review, and critically evaluate the studies they find." (p. 139). Nelson, L. K. (2013). Research in Communication Sciences and Disorders . Plural Publishing.

• Example : The effect of leave policies on increasing fertility: a systematic review:  10.1057/s41599-022-01270-w

Meta-analysis : "Meta-analysis is a method of reviewing research findings in a quantitative fashion by transforming the data from individual studies into what is called an effect size and then pooling and analyzing this information. The basic goal in meta-analysis is to explain why different outcomes have occurred in different studies." (p. 197). Roberts, M. C., & Ilardi, S. S. (2003). Handbook of Research Methods in Clinical Psychology . Blackwell Publishing.

• Example : Employment Instability and Fertility in Europe: A Meta-Analysis:  10.1215/00703370-9164737

Meta-synthesis : "Qualitative meta-synthesis is a type of qualitative study that uses as data the findings from other qualitative studies linked by the same or related topic." (p.312). Zimmer, L. (2006). Qualitative meta-synthesis: A question of dialoguing with texts .  Journal of Advanced Nursing , 53 (3), 311-318.

• Example : Women’s perspectives on career successes and barriers: A qualitative meta-synthesis:  10.1177/05390184221113735

Literature Reviews in the Health Sciences

• UConn Health subject guide on systematic reviews Explanation of the different review types used in health sciences literature as well as tools to help you find the right review type
• << Previous: Getting Started
• Next: How to Pick a Topic >>
• Last Updated: Sep 21, 2022 2:16 PM
• URL: https://guides.lib.uconn.edu/literaturereview

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

• View all journals
• Explore content
• About the journal
• Publish with us
• Sign up for alerts
• CAREER FEATURE
• 04 December 2020
• Correction 09 December 2020

How to write a superb literature review

Andy Tay is a freelance writer based in Singapore.

You can also search for this author in PubMed   Google Scholar

Literature reviews are important resources for scientists. They provide historical context for a field while offering opinions on its future trajectory. Creating them can provide inspiration for one’s own research, as well as some practice in writing. But few scientists are trained in how to write a review — or in what constitutes an excellent one. Even picking the appropriate software to use can be an involved decision (see ‘Tools and techniques’). So Nature asked editors and working scientists with well-cited reviews for their tips.

Access options

Access Nature and 54 other Nature Portfolio journals

Get Nature+, our best-value online-access subscription

24,99 € / 30 days

cancel any time

Subscribe to this journal

Receive 51 print issues and online access

185,98 € per year

only 3,65 € per issue

Rent or buy this article

Prices vary by article type

Prices may be subject to local taxes which are calculated during checkout

doi: https://doi.org/10.1038/d41586-020-03422-x

Interviews have been edited for length and clarity.

Updates & Corrections

Correction 09 December 2020 : An earlier version of the tables in this article included some incorrect details about the programs Zotero, Endnote and Manubot. These have now been corrected.

Hsing, I.-M., Xu, Y. & Zhao, W. Electroanalysis 19 , 755–768 (2007).

Article   Google Scholar  

Ledesma, H. A. et al. Nature Nanotechnol. 14 , 645–657 (2019).

Article   PubMed   Google Scholar  

Brahlek, M., Koirala, N., Bansal, N. & Oh, S. Solid State Commun. 215–216 , 54–62 (2015).

Choi, Y. & Lee, S. Y. Nature Rev. Chem . https://doi.org/10.1038/s41570-020-00221-w (2020).

Download references

Related Articles

• Research management

How I harnessed media engagement to supercharge my research career

Career Column 09 APR 24

How we landed job interviews for professorships straight out of our PhD programmes

Career Column 08 APR 24

Three ways ChatGPT helps me in my academic writing

How two PhD students overcame the odds to snag tenure-track jobs

Adopt universal standards for study adaptation to boost health, education and social-science research

Correspondence 02 APR 24

Is ChatGPT corrupting peer review? Telltale words hint at AI use

News 10 APR 24

Rwanda 30 years on: understanding the horror of genocide

Editorial 09 APR 24

Junior Group Leader Position at IMBA - Institute of Molecular Biotechnology

The Institute of Molecular Biotechnology (IMBA) is one of Europe’s leading institutes for basic research in the life sciences. IMBA is located on t...

Austria (AT)

IMBA - Institute of Molecular Biotechnology

Open Rank Faculty, Center for Public Health Genomics

Center for Public Health Genomics & UVA Comprehensive Cancer Center seek 2 tenure-track faculty members in Cancer Precision Medicine/Precision Health.

Charlottesville, Virginia

Center for Public Health Genomics at the University of Virginia

Husbandry Technician I

Memphis, Tennessee

St. Jude Children's Research Hospital (St. Jude)

Lead Researcher – Department of Bone Marrow Transplantation & Cellular Therapy

Researcher in the center for in vivo imaging and therapy.

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Quick links

• Explore articles by subject
• Guide to authors
• Editorial policies

Libraries | Research Guides

Literature reviews, what is a literature review, learning more about how to do a literature review.

• Planning the Review
• The Research Question
• Choosing Where to Search
• Organizing the Review
• Writing the Review

A literature review is a review and synthesis of existing research on a topic or research question. A literature review is meant to analyze the scholarly literature, make connections across writings and identify strengths, weaknesses, trends, and missing conversations. A literature review should address different aspects of a topic as it relates to your research question. A literature review goes beyond a description or summary of the literature you have read. 

• Sage Research Methods Core Collection This link opens in a new window SAGE Research Methods supports research at all levels by providing material to guide users through every step of the research process. SAGE Research Methods is the ultimate methods library with more than 1000 books, reference works, journal articles, and instructional videos by world-leading academics from across the social sciences, including the largest collection of qualitative methods books available online from any scholarly publisher. – Publisher

• Next: Planning the Review >>
• Last Updated: Jan 17, 2024 10:05 AM
• URL: https://libguides.northwestern.edu/literaturereviews

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings

Preview improvements coming to the PMC website in October 2024. Learn More or Try it out now .

• Advanced Search
• Journal List
• PLoS Comput Biol
• v.9(7); 2013 Jul

Ten Simple Rules for Writing a Literature Review

Marco pautasso.

1 Centre for Functional and Evolutionary Ecology (CEFE), CNRS, Montpellier, France

2 Centre for Biodiversity Synthesis and Analysis (CESAB), FRB, Aix-en-Provence, France

Literature reviews are in great demand in most scientific fields. Their need stems from the ever-increasing output of scientific publications [1] . For example, compared to 1991, in 2008 three, eight, and forty times more papers were indexed in Web of Science on malaria, obesity, and biodiversity, respectively [2] . Given such mountains of papers, scientists cannot be expected to examine in detail every single new paper relevant to their interests [3] . Thus, it is both advantageous and necessary to rely on regular summaries of the recent literature. Although recognition for scientists mainly comes from primary research, timely literature reviews can lead to new synthetic insights and are often widely read [4] . For such summaries to be useful, however, they need to be compiled in a professional way [5] .

When starting from scratch, reviewing the literature can require a titanic amount of work. That is why researchers who have spent their career working on a certain research issue are in a perfect position to review that literature. Some graduate schools are now offering courses in reviewing the literature, given that most research students start their project by producing an overview of what has already been done on their research issue [6] . However, it is likely that most scientists have not thought in detail about how to approach and carry out a literature review.

Reviewing the literature requires the ability to juggle multiple tasks, from finding and evaluating relevant material to synthesising information from various sources, from critical thinking to paraphrasing, evaluating, and citation skills [7] . In this contribution, I share ten simple rules I learned working on about 25 literature reviews as a PhD and postdoctoral student. Ideas and insights also come from discussions with coauthors and colleagues, as well as feedback from reviewers and editors.

Rule 1: Define a Topic and Audience

How to choose which topic to review? There are so many issues in contemporary science that you could spend a lifetime of attending conferences and reading the literature just pondering what to review. On the one hand, if you take several years to choose, several other people may have had the same idea in the meantime. On the other hand, only a well-considered topic is likely to lead to a brilliant literature review [8] . The topic must at least be:

• interesting to you (ideally, you should have come across a series of recent papers related to your line of work that call for a critical summary),
• an important aspect of the field (so that many readers will be interested in the review and there will be enough material to write it), and
• a well-defined issue (otherwise you could potentially include thousands of publications, which would make the review unhelpful).

Ideas for potential reviews may come from papers providing lists of key research questions to be answered [9] , but also from serendipitous moments during desultory reading and discussions. In addition to choosing your topic, you should also select a target audience. In many cases, the topic (e.g., web services in computational biology) will automatically define an audience (e.g., computational biologists), but that same topic may also be of interest to neighbouring fields (e.g., computer science, biology, etc.).

Rule 2: Search and Re-search the Literature

After having chosen your topic and audience, start by checking the literature and downloading relevant papers. Five pieces of advice here:

• keep track of the search items you use (so that your search can be replicated [10] ),
• keep a list of papers whose pdfs you cannot access immediately (so as to retrieve them later with alternative strategies),
• use a paper management system (e.g., Mendeley, Papers, Qiqqa, Sente),
• define early in the process some criteria for exclusion of irrelevant papers (these criteria can then be described in the review to help define its scope), and
• do not just look for research papers in the area you wish to review, but also seek previous reviews.

The chances are high that someone will already have published a literature review ( Figure 1 ), if not exactly on the issue you are planning to tackle, at least on a related topic. If there are already a few or several reviews of the literature on your issue, my advice is not to give up, but to carry on with your own literature review,

The bottom-right situation (many literature reviews but few research papers) is not just a theoretical situation; it applies, for example, to the study of the impacts of climate change on plant diseases, where there appear to be more literature reviews than research studies [33] .

• discussing in your review the approaches, limitations, and conclusions of past reviews,
• trying to find a new angle that has not been covered adequately in the previous reviews, and
• incorporating new material that has inevitably accumulated since their appearance.

When searching the literature for pertinent papers and reviews, the usual rules apply:

• be thorough,
• use different keywords and database sources (e.g., DBLP, Google Scholar, ISI Proceedings, JSTOR Search, Medline, Scopus, Web of Science), and
• look at who has cited past relevant papers and book chapters.

Rule 3: Take Notes While Reading

If you read the papers first, and only afterwards start writing the review, you will need a very good memory to remember who wrote what, and what your impressions and associations were while reading each single paper. My advice is, while reading, to start writing down interesting pieces of information, insights about how to organize the review, and thoughts on what to write. This way, by the time you have read the literature you selected, you will already have a rough draft of the review.

Of course, this draft will still need much rewriting, restructuring, and rethinking to obtain a text with a coherent argument [11] , but you will have avoided the danger posed by staring at a blank document. Be careful when taking notes to use quotation marks if you are provisionally copying verbatim from the literature. It is advisable then to reformulate such quotes with your own words in the final draft. It is important to be careful in noting the references already at this stage, so as to avoid misattributions. Using referencing software from the very beginning of your endeavour will save you time.

Rule 4: Choose the Type of Review You Wish to Write

After having taken notes while reading the literature, you will have a rough idea of the amount of material available for the review. This is probably a good time to decide whether to go for a mini- or a full review. Some journals are now favouring the publication of rather short reviews focusing on the last few years, with a limit on the number of words and citations. A mini-review is not necessarily a minor review: it may well attract more attention from busy readers, although it will inevitably simplify some issues and leave out some relevant material due to space limitations. A full review will have the advantage of more freedom to cover in detail the complexities of a particular scientific development, but may then be left in the pile of the very important papers “to be read” by readers with little time to spare for major monographs.

There is probably a continuum between mini- and full reviews. The same point applies to the dichotomy of descriptive vs. integrative reviews. While descriptive reviews focus on the methodology, findings, and interpretation of each reviewed study, integrative reviews attempt to find common ideas and concepts from the reviewed material [12] . A similar distinction exists between narrative and systematic reviews: while narrative reviews are qualitative, systematic reviews attempt to test a hypothesis based on the published evidence, which is gathered using a predefined protocol to reduce bias [13] , [14] . When systematic reviews analyse quantitative results in a quantitative way, they become meta-analyses. The choice between different review types will have to be made on a case-by-case basis, depending not just on the nature of the material found and the preferences of the target journal(s), but also on the time available to write the review and the number of coauthors [15] .

Rule 5: Keep the Review Focused, but Make It of Broad Interest

Whether your plan is to write a mini- or a full review, it is good advice to keep it focused 16 , 17 . Including material just for the sake of it can easily lead to reviews that are trying to do too many things at once. The need to keep a review focused can be problematic for interdisciplinary reviews, where the aim is to bridge the gap between fields [18] . If you are writing a review on, for example, how epidemiological approaches are used in modelling the spread of ideas, you may be inclined to include material from both parent fields, epidemiology and the study of cultural diffusion. This may be necessary to some extent, but in this case a focused review would only deal in detail with those studies at the interface between epidemiology and the spread of ideas.

While focus is an important feature of a successful review, this requirement has to be balanced with the need to make the review relevant to a broad audience. This square may be circled by discussing the wider implications of the reviewed topic for other disciplines.

Rule 6: Be Critical and Consistent

Reviewing the literature is not stamp collecting. A good review does not just summarize the literature, but discusses it critically, identifies methodological problems, and points out research gaps [19] . After having read a review of the literature, a reader should have a rough idea of:

• the major achievements in the reviewed field,
• the main areas of debate, and
• the outstanding research questions.

It is challenging to achieve a successful review on all these fronts. A solution can be to involve a set of complementary coauthors: some people are excellent at mapping what has been achieved, some others are very good at identifying dark clouds on the horizon, and some have instead a knack at predicting where solutions are going to come from. If your journal club has exactly this sort of team, then you should definitely write a review of the literature! In addition to critical thinking, a literature review needs consistency, for example in the choice of passive vs. active voice and present vs. past tense.

Rule 7: Find a Logical Structure

Like a well-baked cake, a good review has a number of telling features: it is worth the reader's time, timely, systematic, well written, focused, and critical. It also needs a good structure. With reviews, the usual subdivision of research papers into introduction, methods, results, and discussion does not work or is rarely used. However, a general introduction of the context and, toward the end, a recapitulation of the main points covered and take-home messages make sense also in the case of reviews. For systematic reviews, there is a trend towards including information about how the literature was searched (database, keywords, time limits) [20] .

How can you organize the flow of the main body of the review so that the reader will be drawn into and guided through it? It is generally helpful to draw a conceptual scheme of the review, e.g., with mind-mapping techniques. Such diagrams can help recognize a logical way to order and link the various sections of a review [21] . This is the case not just at the writing stage, but also for readers if the diagram is included in the review as a figure. A careful selection of diagrams and figures relevant to the reviewed topic can be very helpful to structure the text too [22] .

Rule 8: Make Use of Feedback

Reviews of the literature are normally peer-reviewed in the same way as research papers, and rightly so [23] . As a rule, incorporating feedback from reviewers greatly helps improve a review draft. Having read the review with a fresh mind, reviewers may spot inaccuracies, inconsistencies, and ambiguities that had not been noticed by the writers due to rereading the typescript too many times. It is however advisable to reread the draft one more time before submission, as a last-minute correction of typos, leaps, and muddled sentences may enable the reviewers to focus on providing advice on the content rather than the form.

Feedback is vital to writing a good review, and should be sought from a variety of colleagues, so as to obtain a diversity of views on the draft. This may lead in some cases to conflicting views on the merits of the paper, and on how to improve it, but such a situation is better than the absence of feedback. A diversity of feedback perspectives on a literature review can help identify where the consensus view stands in the landscape of the current scientific understanding of an issue [24] .

Rule 9: Include Your Own Relevant Research, but Be Objective

In many cases, reviewers of the literature will have published studies relevant to the review they are writing. This could create a conflict of interest: how can reviewers report objectively on their own work [25] ? Some scientists may be overly enthusiastic about what they have published, and thus risk giving too much importance to their own findings in the review. However, bias could also occur in the other direction: some scientists may be unduly dismissive of their own achievements, so that they will tend to downplay their contribution (if any) to a field when reviewing it.

In general, a review of the literature should neither be a public relations brochure nor an exercise in competitive self-denial. If a reviewer is up to the job of producing a well-organized and methodical review, which flows well and provides a service to the readership, then it should be possible to be objective in reviewing one's own relevant findings. In reviews written by multiple authors, this may be achieved by assigning the review of the results of a coauthor to different coauthors.

Rule 10: Be Up-to-Date, but Do Not Forget Older Studies

Given the progressive acceleration in the publication of scientific papers, today's reviews of the literature need awareness not just of the overall direction and achievements of a field of inquiry, but also of the latest studies, so as not to become out-of-date before they have been published. Ideally, a literature review should not identify as a major research gap an issue that has just been addressed in a series of papers in press (the same applies, of course, to older, overlooked studies (“sleeping beauties” [26] )). This implies that literature reviewers would do well to keep an eye on electronic lists of papers in press, given that it can take months before these appear in scientific databases. Some reviews declare that they have scanned the literature up to a certain point in time, but given that peer review can be a rather lengthy process, a full search for newly appeared literature at the revision stage may be worthwhile. Assessing the contribution of papers that have just appeared is particularly challenging, because there is little perspective with which to gauge their significance and impact on further research and society.

Inevitably, new papers on the reviewed topic (including independently written literature reviews) will appear from all quarters after the review has been published, so that there may soon be the need for an updated review. But this is the nature of science [27] – [32] . I wish everybody good luck with writing a review of the literature.

Acknowledgments

Many thanks to M. Barbosa, K. Dehnen-Schmutz, T. Döring, D. Fontaneto, M. Garbelotto, O. Holdenrieder, M. Jeger, D. Lonsdale, A. MacLeod, P. Mills, M. Moslonka-Lefebvre, G. Stancanelli, P. Weisberg, and X. Xu for insights and discussions, and to P. Bourne, T. Matoni, and D. Smith for helpful comments on a previous draft.

Funding Statement

This work was funded by the French Foundation for Research on Biodiversity (FRB) through its Centre for Synthesis and Analysis of Biodiversity data (CESAB), as part of the NETSEED research project. The funders had no role in the preparation of the manuscript.

Learn how to write a review of literature

What is a review of literature.

The format of a review of literature may vary from discipline to discipline and from assignment to assignment.

A review may be a self-contained unit — an end in itself — or a preface to and rationale for engaging in primary research. A review is a required part of grant and research proposals and often a chapter in theses and dissertations.

Generally, the purpose of a review is to analyze critically a segment of a published body of knowledge through summary, classification, and comparison of prior research studies, reviews of literature, and theoretical articles.

Writing the introduction

In the introduction, you should:

Define or identify the general topic, issue, or area of concern, thus providing an appropriate context for reviewing the literature.

Point out overall trends in what has been published about the topic; or conflicts in theory, methodology, evidence, and conclusions; or gaps in research and scholarship; or a single problem or new perspective of immediate interest.

Establish the writer’s reason (point of view) for reviewing the literature; explain the criteria to be used in analyzing and comparing literature and the organization of the review (sequence); and, when necessary, state why certain literature is or is not included (scope).

Writing the body

In the body, you should:

Group research studies and other types of literature (reviews, theoretical articles, case studies, etc.) according to common denominators such as qualitative versus quantitative approaches, conclusions of authors, specific purpose or objective, chronology, etc.

Summarize individual studies or articles with as much or as little detail as each merits according to its comparative importance in the literature, remembering that space (length) denotes significance.

Provide the reader with strong “umbrella” sentences at beginnings of paragraphs, “signposts” throughout, and brief “so what” summary sentences at intermediate points in the review to aid in understanding comparisons and analyses.

Writing the conclusion

In the conclusion, you should:

Summarize major contributions of significant studies and articles to the body of knowledge under review, maintaining the focus established in the introduction.

Evaluate the current “state of the art” for the body of knowledge reviewed, pointing out major methodological flaws or gaps in research, inconsistencies in theory and findings, and areas or issues pertinent to future study.

Conclude by providing some insight into the relationship between the central topic of the literature review and a larger area of study such as a discipline, a scientific endeavor, or a profession.

For further information see our handouts on Writing a Critical Review of a Nonfiction Book or Article or Reading a Book to Review It .

To learn more about literature reviews, take a look at our workshop on Writing Literature Reviews of Published Research.

Sample Literature Reviews

An important strategy for learning how to compose literature reviews in your field or within a specific genre is to locate and analyze representative examples. The following collection of annotated sample literature reviews written and co-written by colleagues associated with UW-Madison showcases how these reviews can do different kind of work for different purposes. Use these successful examples as a starting point for understanding how other writers have approached the challenging and important task of situating their idea in the context of established research.

• Sample 1 (PDF) A brief literature review within a political scientists’  National Science Foundation Graduate Research Fellowship  grant
• Sample 2 (PDF) A several-page literature review at the beginning of a published, academic article about philosophy
• Sample 3 (PDF) A brief literature review at the beginning of a published, academic article about photochemistry

Academic and Professional Writing

This is an accordion element with a series of buttons that open and close related content panels.

Analysis Papers

Reading Poetry

A Short Guide to Close Reading for Literary Analysis

Using Literary Quotations

Play Reviews

Writing a Rhetorical Précis to Analyze Nonfiction Texts

Incorporating Interview Data

Grant Proposals

Planning and Writing a Grant Proposal: The Basics

Additional Resources for Grants and Proposal Writing

Job Materials and Application Essays

Writing Personal Statements for Ph.D. Programs

• Before you begin: useful tips for writing your essay
• Guided brainstorming exercises
• Get more help with your essay
• Frequently Asked Questions

Resume Writing Tips

CV Writing Tips

Cover Letters

Business Letters

Proposals and Dissertations

Resources for Proposal Writers

Resources for Dissertators

Research Papers

Planning and Writing Research Papers

Quoting and Paraphrasing

Writing Annotated Bibliographies

Creating Poster Presentations

Writing an Abstract for Your Research Paper

Thank-You Notes

Advice for Students Writing Thank-You Notes to Donors

Reading for a Review

Critical Reviews

Writing a Review of Literature

Scientific Reports

Scientific Report Format

Sample Lab Assignment

Writing for the Web

Writing an Effective Blog Post

Writing for Social Media: A Guide for Academics

• USC Libraries
• Research Guides

Organizing Your Social Sciences Research Paper

• 5. The Literature Review
• Purpose of Guide
• Design Flaws to Avoid
• Independent and Dependent Variables
• Glossary of Research Terms
• Reading Research Effectively
• Narrowing a Topic Idea
• Broadening a Topic Idea
• Extending the Timeliness of a Topic Idea
• Academic Writing Style
• Applying Critical Thinking
• Choosing a Title
• Making an Outline
• Paragraph Development
• Research Process Video Series
• Executive Summary
• The C.A.R.S. Model
• Background Information
• The Research Problem/Question
• Theoretical Framework
• Citation Tracking
• Content Alert Services
• Evaluating Sources
• Primary Sources
• Secondary Sources
• Tiertiary Sources
• Scholarly vs. Popular Publications
• Qualitative Methods
• Quantitative Methods
• Insiderness
• Using Non-Textual Elements
• Limitations of the Study
• Common Grammar Mistakes
• Writing Concisely
• Avoiding Plagiarism
• Footnotes or Endnotes?
• Further Readings
• Generative AI and Writing
• USC Libraries Tutorials and Other Guides
• Bibliography

A literature review surveys prior research published in books, scholarly articles, and any other sources relevant to a particular issue, area of research, or theory, and by so doing, provides a description, summary, and critical evaluation of these works in relation to the research problem being investigated. Literature reviews are designed to provide an overview of sources you have used in researching a particular topic and to demonstrate to your readers how your research fits within existing scholarship about the topic.

Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . Fourth edition. Thousand Oaks, CA: SAGE, 2014.

Importance of a Good Literature Review

A literature review may consist of simply a summary of key sources, but in the social sciences, a literature review usually has an organizational pattern and combines both summary and synthesis, often within specific conceptual categories . A summary is a recap of the important information of the source, but a synthesis is a re-organization, or a reshuffling, of that information in a way that informs how you are planning to investigate a research problem. The analytical features of a literature review might:

• Give a new interpretation of old material or combine new with old interpretations,
• Trace the intellectual progression of the field, including major debates,
• Depending on the situation, evaluate the sources and advise the reader on the most pertinent or relevant research, or
• Usually in the conclusion of a literature review, identify where gaps exist in how a problem has been researched to date.

Given this, the purpose of a literature review is to:

• Place each work in the context of its contribution to understanding the research problem being studied.
• Describe the relationship of each work to the others under consideration.
• Identify new ways to interpret prior research.
• Reveal any gaps that exist in the literature.
• Resolve conflicts amongst seemingly contradictory previous studies.
• Identify areas of prior scholarship to prevent duplication of effort.
• Point the way in fulfilling a need for additional research.
• Locate your own research within the context of existing literature [very important].

Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper. 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Jesson, Jill. Doing Your Literature Review: Traditional and Systematic Techniques . Los Angeles, CA: SAGE, 2011; Knopf, Jeffrey W. "Doing a Literature Review." PS: Political Science and Politics 39 (January 2006): 127-132; Ridley, Diana. The Literature Review: A Step-by-Step Guide for Students . 2nd ed. Los Angeles, CA: SAGE, 2012.

Types of Literature Reviews

It is important to think of knowledge in a given field as consisting of three layers. First, there are the primary studies that researchers conduct and publish. Second are the reviews of those studies that summarize and offer new interpretations built from and often extending beyond the primary studies. Third, there are the perceptions, conclusions, opinion, and interpretations that are shared informally among scholars that become part of the body of epistemological traditions within the field.

In composing a literature review, it is important to note that it is often this third layer of knowledge that is cited as "true" even though it often has only a loose relationship to the primary studies and secondary literature reviews. Given this, while literature reviews are designed to provide an overview and synthesis of pertinent sources you have explored, there are a number of approaches you could adopt depending upon the type of analysis underpinning your study.

Argumentative Review This form examines literature selectively in order to support or refute an argument, deeply embedded assumption, or philosophical problem already established in the literature. The purpose is to develop a body of literature that establishes a contrarian viewpoint. Given the value-laden nature of some social science research [e.g., educational reform; immigration control], argumentative approaches to analyzing the literature can be a legitimate and important form of discourse. However, note that they can also introduce problems of bias when they are used to make summary claims of the sort found in systematic reviews [see below].

Integrative Review Considered a form of research that reviews, critiques, and synthesizes representative literature on a topic in an integrated way such that new frameworks and perspectives on the topic are generated. The body of literature includes all studies that address related or identical hypotheses or research problems. A well-done integrative review meets the same standards as primary research in regard to clarity, rigor, and replication. This is the most common form of review in the social sciences.

Historical Review Few things rest in isolation from historical precedent. Historical literature reviews focus on examining research throughout a period of time, often starting with the first time an issue, concept, theory, phenomena emerged in the literature, then tracing its evolution within the scholarship of a discipline. The purpose is to place research in a historical context to show familiarity with state-of-the-art developments and to identify the likely directions for future research.

Methodological Review A review does not always focus on what someone said [findings], but how they came about saying what they say [method of analysis]. Reviewing methods of analysis provides a framework of understanding at different levels [i.e. those of theory, substantive fields, research approaches, and data collection and analysis techniques], how researchers draw upon a wide variety of knowledge ranging from the conceptual level to practical documents for use in fieldwork in the areas of ontological and epistemological consideration, quantitative and qualitative integration, sampling, interviewing, data collection, and data analysis. This approach helps highlight ethical issues which you should be aware of and consider as you go through your own study.

Systematic Review This form consists of an overview of existing evidence pertinent to a clearly formulated research question, which uses pre-specified and standardized methods to identify and critically appraise relevant research, and to collect, report, and analyze data from the studies that are included in the review. The goal is to deliberately document, critically evaluate, and summarize scientifically all of the research about a clearly defined research problem . Typically it focuses on a very specific empirical question, often posed in a cause-and-effect form, such as "To what extent does A contribute to B?" This type of literature review is primarily applied to examining prior research studies in clinical medicine and allied health fields, but it is increasingly being used in the social sciences.

Theoretical Review The purpose of this form is to examine the corpus of theory that has accumulated in regard to an issue, concept, theory, phenomena. The theoretical literature review helps to establish what theories already exist, the relationships between them, to what degree the existing theories have been investigated, and to develop new hypotheses to be tested. Often this form is used to help establish a lack of appropriate theories or reveal that current theories are inadequate for explaining new or emerging research problems. The unit of analysis can focus on a theoretical concept or a whole theory or framework.

NOTE : Most often the literature review will incorporate some combination of types. For example, a review that examines literature supporting or refuting an argument, assumption, or philosophical problem related to the research problem will also need to include writing supported by sources that establish the history of these arguments in the literature.

Baumeister, Roy F. and Mark R. Leary. "Writing Narrative Literature Reviews."  Review of General Psychology 1 (September 1997): 311-320; Mark R. Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Kennedy, Mary M. "Defining a Literature." Educational Researcher 36 (April 2007): 139-147; Petticrew, Mark and Helen Roberts. Systematic Reviews in the Social Sciences: A Practical Guide . Malden, MA: Blackwell Publishers, 2006; Torracro, Richard. "Writing Integrative Literature Reviews: Guidelines and Examples." Human Resource Development Review 4 (September 2005): 356-367; Rocco, Tonette S. and Maria S. Plakhotnik. "Literature Reviews, Conceptual Frameworks, and Theoretical Frameworks: Terms, Functions, and Distinctions." Human Ressource Development Review 8 (March 2008): 120-130; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016.

Structure and Writing Style

I.  Thinking About Your Literature Review

The structure of a literature review should include the following in support of understanding the research problem :

• An overview of the subject, issue, or theory under consideration, along with the objectives of the literature review,
• Division of works under review into themes or categories [e.g. works that support a particular position, those against, and those offering alternative approaches entirely],
• An explanation of how each work is similar to and how it varies from the others,
• Conclusions as to which pieces are best considered in their argument, are most convincing of their opinions, and make the greatest contribution to the understanding and development of their area of research.

The critical evaluation of each work should consider :

• Provenance -- what are the author's credentials? Are the author's arguments supported by evidence [e.g. primary historical material, case studies, narratives, statistics, recent scientific findings]?
• Methodology -- were the techniques used to identify, gather, and analyze the data appropriate to addressing the research problem? Was the sample size appropriate? Were the results effectively interpreted and reported?
• Objectivity -- is the author's perspective even-handed or prejudicial? Is contrary data considered or is certain pertinent information ignored to prove the author's point?
• Persuasiveness -- which of the author's theses are most convincing or least convincing?
• Validity -- are the author's arguments and conclusions convincing? Does the work ultimately contribute in any significant way to an understanding of the subject?

II.  Development of the Literature Review

Four Basic Stages of Writing 1.  Problem formulation -- which topic or field is being examined and what are its component issues? 2.  Literature search -- finding materials relevant to the subject being explored. 3.  Data evaluation -- determining which literature makes a significant contribution to the understanding of the topic. 4.  Analysis and interpretation -- discussing the findings and conclusions of pertinent literature.

Consider the following issues before writing the literature review: Clarify If your assignment is not specific about what form your literature review should take, seek clarification from your professor by asking these questions: 1.  Roughly how many sources would be appropriate to include? 2.  What types of sources should I review (books, journal articles, websites; scholarly versus popular sources)? 3.  Should I summarize, synthesize, or critique sources by discussing a common theme or issue? 4.  Should I evaluate the sources in any way beyond evaluating how they relate to understanding the research problem? 5.  Should I provide subheadings and other background information, such as definitions and/or a history? Find Models Use the exercise of reviewing the literature to examine how authors in your discipline or area of interest have composed their literature review sections. Read them to get a sense of the types of themes you might want to look for in your own research or to identify ways to organize your final review. The bibliography or reference section of sources you've already read, such as required readings in the course syllabus, are also excellent entry points into your own research. Narrow the Topic The narrower your topic, the easier it will be to limit the number of sources you need to read in order to obtain a good survey of relevant resources. Your professor will probably not expect you to read everything that's available about the topic, but you'll make the act of reviewing easier if you first limit scope of the research problem. A good strategy is to begin by searching the USC Libraries Catalog for recent books about the topic and review the table of contents for chapters that focuses on specific issues. You can also review the indexes of books to find references to specific issues that can serve as the focus of your research. For example, a book surveying the history of the Israeli-Palestinian conflict may include a chapter on the role Egypt has played in mediating the conflict, or look in the index for the pages where Egypt is mentioned in the text. Consider Whether Your Sources are Current Some disciplines require that you use information that is as current as possible. This is particularly true in disciplines in medicine and the sciences where research conducted becomes obsolete very quickly as new discoveries are made. However, when writing a review in the social sciences, a survey of the history of the literature may be required. In other words, a complete understanding the research problem requires you to deliberately examine how knowledge and perspectives have changed over time. Sort through other current bibliographies or literature reviews in the field to get a sense of what your discipline expects. You can also use this method to explore what is considered by scholars to be a "hot topic" and what is not.

III.  Ways to Organize Your Literature Review

Chronology of Events If your review follows the chronological method, you could write about the materials according to when they were published. This approach should only be followed if a clear path of research building on previous research can be identified and that these trends follow a clear chronological order of development. For example, a literature review that focuses on continuing research about the emergence of German economic power after the fall of the Soviet Union. By Publication Order your sources by publication chronology, then, only if the order demonstrates a more important trend. For instance, you could order a review of literature on environmental studies of brown fields if the progression revealed, for example, a change in the soil collection practices of the researchers who wrote and/or conducted the studies. Thematic [“conceptual categories”] A thematic literature review is the most common approach to summarizing prior research in the social and behavioral sciences. Thematic reviews are organized around a topic or issue, rather than the progression of time, although the progression of time may still be incorporated into a thematic review. For example, a review of the Internet’s impact on American presidential politics could focus on the development of online political satire. While the study focuses on one topic, the Internet’s impact on American presidential politics, it would still be organized chronologically reflecting technological developments in media. The difference in this example between a "chronological" and a "thematic" approach is what is emphasized the most: themes related to the role of the Internet in presidential politics. Note that more authentic thematic reviews tend to break away from chronological order. A review organized in this manner would shift between time periods within each section according to the point being made. Methodological A methodological approach focuses on the methods utilized by the researcher. For the Internet in American presidential politics project, one methodological approach would be to look at cultural differences between the portrayal of American presidents on American, British, and French websites. Or the review might focus on the fundraising impact of the Internet on a particular political party. A methodological scope will influence either the types of documents in the review or the way in which these documents are discussed.

Other Sections of Your Literature Review Once you've decided on the organizational method for your literature review, the sections you need to include in the paper should be easy to figure out because they arise from your organizational strategy. In other words, a chronological review would have subsections for each vital time period; a thematic review would have subtopics based upon factors that relate to the theme or issue. However, sometimes you may need to add additional sections that are necessary for your study, but do not fit in the organizational strategy of the body. What other sections you include in the body is up to you. However, only include what is necessary for the reader to locate your study within the larger scholarship about the research problem.

Here are examples of other sections, usually in the form of a single paragraph, you may need to include depending on the type of review you write:

• Current Situation : Information necessary to understand the current topic or focus of the literature review.
• Sources Used : Describes the methods and resources [e.g., databases] you used to identify the literature you reviewed.
• History : The chronological progression of the field, the research literature, or an idea that is necessary to understand the literature review, if the body of the literature review is not already a chronology.
• Selection Methods : Criteria you used to select (and perhaps exclude) sources in your literature review. For instance, you might explain that your review includes only peer-reviewed [i.e., scholarly] sources.
• Standards : Description of the way in which you present your information.
• Questions for Further Research : What questions about the field has the review sparked? How will you further your research as a result of the review?

IV.  Writing Your Literature Review

Once you've settled on how to organize your literature review, you're ready to write each section. When writing your review, keep in mind these issues.

Use Evidence A literature review section is, in this sense, just like any other academic research paper. Your interpretation of the available sources must be backed up with evidence [citations] that demonstrates that what you are saying is valid. Be Selective Select only the most important points in each source to highlight in the review. The type of information you choose to mention should relate directly to the research problem, whether it is thematic, methodological, or chronological. Related items that provide additional information, but that are not key to understanding the research problem, can be included in a list of further readings . Use Quotes Sparingly Some short quotes are appropriate if you want to emphasize a point, or if what an author stated cannot be easily paraphrased. Sometimes you may need to quote certain terminology that was coined by the author, is not common knowledge, or taken directly from the study. Do not use extensive quotes as a substitute for using your own words in reviewing the literature. Summarize and Synthesize Remember to summarize and synthesize your sources within each thematic paragraph as well as throughout the review. Recapitulate important features of a research study, but then synthesize it by rephrasing the study's significance and relating it to your own work and the work of others. Keep Your Own Voice While the literature review presents others' ideas, your voice [the writer's] should remain front and center. For example, weave references to other sources into what you are writing but maintain your own voice by starting and ending the paragraph with your own ideas and wording. Use Caution When Paraphrasing When paraphrasing a source that is not your own, be sure to represent the author's information or opinions accurately and in your own words. Even when paraphrasing an author’s work, you still must provide a citation to that work.

V.  Common Mistakes to Avoid

These are the most common mistakes made in reviewing social science research literature.

• Sources in your literature review do not clearly relate to the research problem;
• You do not take sufficient time to define and identify the most relevant sources to use in the literature review related to the research problem;
• Relies exclusively on secondary analytical sources rather than including relevant primary research studies or data;
• Uncritically accepts another researcher's findings and interpretations as valid, rather than examining critically all aspects of the research design and analysis;
• Does not describe the search procedures that were used in identifying the literature to review;
• Reports isolated statistical results rather than synthesizing them in chi-squared or meta-analytic methods; and,
• Only includes research that validates assumptions and does not consider contrary findings and alternative interpretations found in the literature.

Cook, Kathleen E. and Elise Murowchick. “Do Literature Review Skills Transfer from One Course to Another?” Psychology Learning and Teaching 13 (March 2014): 3-11; Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Jesson, Jill. Doing Your Literature Review: Traditional and Systematic Techniques . London: SAGE, 2011; Literature Review Handout. Online Writing Center. Liberty University; Literature Reviews. The Writing Center. University of North Carolina; Onwuegbuzie, Anthony J. and Rebecca Frels. Seven Steps to a Comprehensive Literature Review: A Multimodal and Cultural Approach . Los Angeles, CA: SAGE, 2016; Ridley, Diana. The Literature Review: A Step-by-Step Guide for Students . 2nd ed. Los Angeles, CA: SAGE, 2012; Randolph, Justus J. “A Guide to Writing the Dissertation Literature Review." Practical Assessment, Research, and Evaluation. vol. 14, June 2009; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016; Taylor, Dena. The Literature Review: A Few Tips On Conducting It. University College Writing Centre. University of Toronto; Writing a Literature Review. Academic Skills Centre. University of Canberra.

Writing Tip

Break Out of Your Disciplinary Box!

Thinking interdisciplinarily about a research problem can be a rewarding exercise in applying new ideas, theories, or concepts to an old problem. For example, what might cultural anthropologists say about the continuing conflict in the Middle East? In what ways might geographers view the need for better distribution of social service agencies in large cities than how social workers might study the issue? You don’t want to substitute a thorough review of core research literature in your discipline for studies conducted in other fields of study. However, particularly in the social sciences, thinking about research problems from multiple vectors is a key strategy for finding new solutions to a problem or gaining a new perspective. Consult with a librarian about identifying research databases in other disciplines; almost every field of study has at least one comprehensive database devoted to indexing its research literature.

Frodeman, Robert. The Oxford Handbook of Interdisciplinarity . New York: Oxford University Press, 2010.

Another Writing Tip

Don't Just Review for Content!

While conducting a review of the literature, maximize the time you devote to writing this part of your paper by thinking broadly about what you should be looking for and evaluating. Review not just what scholars are saying, but how are they saying it. Some questions to ask:

• How are they organizing their ideas?
• What methods have they used to study the problem?
• What theories have been used to explain, predict, or understand their research problem?
• What sources have they cited to support their conclusions?
• How have they used non-textual elements [e.g., charts, graphs, figures, etc.] to illustrate key points?

When you begin to write your literature review section, you'll be glad you dug deeper into how the research was designed and constructed because it establishes a means for developing more substantial analysis and interpretation of the research problem.

Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1 998.

Yet Another Writing Tip

When Do I Know I Can Stop Looking and Move On?

Here are several strategies you can utilize to assess whether you've thoroughly reviewed the literature:

• Look for repeating patterns in the research findings . If the same thing is being said, just by different people, then this likely demonstrates that the research problem has hit a conceptual dead end. At this point consider: Does your study extend current research?  Does it forge a new path? Or, does is merely add more of the same thing being said?
• Look at sources the authors cite to in their work . If you begin to see the same researchers cited again and again, then this is often an indication that no new ideas have been generated to address the research problem.
• Search Google Scholar to identify who has subsequently cited leading scholars already identified in your literature review [see next sub-tab]. This is called citation tracking and there are a number of sources that can help you identify who has cited whom, particularly scholars from outside of your discipline. Here again, if the same authors are being cited again and again, this may indicate no new literature has been written on the topic.

Onwuegbuzie, Anthony J. and Rebecca Frels. Seven Steps to a Comprehensive Literature Review: A Multimodal and Cultural Approach . Los Angeles, CA: Sage, 2016; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016.

• << Previous: Theoretical Framework
• Next: Citation Tracking >>
• Last Updated: Apr 11, 2024 1:27 PM
• URL: https://libguides.usc.edu/writingguide

Literature Review - what is a Literature Review, why it is important and how it is done

What are literature reviews, goals of literature reviews, types of literature reviews, about this guide/licence.

• Strategies to Find Sources
• Evaluating Literature Reviews and Sources
• Tips for Writing Literature Reviews
• Writing Literature Review: Useful Sites
• Citation Resources
• Other Academic Writings
• Useful Resources

Help is Just a Click Away

Search our FAQ Knowledge base, ask a question, chat, send comments...

Go to LibAnswers

 What is a literature review? "A literature review is an account of what has been published on a topic by accredited scholars and researchers. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available, or a set of summaries. " - Quote from Taylor, D. (n.d) "The literature review: A few tips on conducting it"

Source NC State University Libraries. This video is published under a Creative Commons 3.0 BY-NC-SA US license.

What are the goals of creating a Literature Review?

• To develop a theory or evaluate an existing theory
• To summarize the historical or existing state of a research topic
• Identify a problem in a field of research 

- Baumeister, R.F. & Leary, M.R. (1997). "Writing narrative literature reviews," Review of General Psychology , 1(3), 311-320.

When do you need to write a Literature Review?

• When writing a prospectus or a thesis/dissertation
• When writing a research paper
• When writing a grant proposal

In all these cases you need to dedicate a chapter in these works to showcase what have been written about your research topic and to point out how your own research will shed a new light into these body of scholarship.

Literature reviews are also written as standalone articles as a way to survey a particular research topic in-depth. This type of literature reviews look at a topic from a historical perspective to see how the understanding of the topic have change through time.

What kinds of literature reviews are written?

• Narrative Review: The purpose of this type of review is to describe the current state of the research on a specific topic/research and to offer a critical analysis of the literature reviewed. Studies are grouped by research/theoretical categories, and themes and trends, strengths and weakness, and gaps are identified. The review ends with a conclusion section which summarizes the findings regarding the state of the research of the specific study, the gaps identify and if applicable, explains how the author's research will address gaps identify in the review and expand the knowledge on the topic reviewed.
• Book review essays/ Historiographical review essays : This is a type of review that focus on a small set of research books on a particular topic " to locate these books within current scholarship, critical methodologies, and approaches" in the field. - LARR
• Systematic review : "The authors of a systematic review use a specific procedure to search the research literature, select the studies to include in their review, and critically evaluate the studies they find." (p. 139). Nelson, L.K. (2013). Research in Communication Sciences and Disorders . San Diego, CA: Plural Publishing.
• Meta-analysis : "Meta-analysis is a method of reviewing research findings in a quantitative fashion by transforming the data from individual studies into what is called an effect size and then pooling and analyzing this information. The basic goal in meta-analysis is to explain why different outcomes have occurred in different studies." (p. 197). Roberts, M.C. & Ilardi, S.S. (2003). Handbook of Research Methods in Clinical Psychology . Malden, MA: Blackwell Pub.
• Meta-synthesis : "Qualitative meta-synthesis is a type of qualitative study that uses as data the findings from other qualitative studies linked by the same or related topic." (p.312). Zimmer, L. (2006). "Qualitative meta-synthesis: A question of dialoguing with texts," Journal of Advanced Nursing , 53(3), 311-318.

Guide adapted from "Literature Review" , a guide developed by Marisol Ramos used under CC BY 4.0 /modified from original.

• Next: Strategies to Find Sources >>
• Last Updated: Apr 10, 2024 3:27 PM
• URL: https://lit.libguides.com/Literature-Review

The Library, Technological University of the Shannon: Midwest

How to Write a Literature Review

What is a literature review.

• What Is the Literature
• Writing the Review

A literature review is much more than an annotated bibliography or a list of separate reviews of articles and books. It is a critical, analytical summary and synthesis of the current knowledge of a topic. Thus it should compare and relate different theories, findings, etc, rather than just summarize them individually. In addition, it should have a particular focus or theme to organize the review. It does not have to be an exhaustive account of everything published on the topic, but it should discuss all the significant academic literature and other relevant sources important for that focus.

This is meant to be a general guide to writing a literature review: ways to structure one, what to include, how it supplements other research. For more specific help on writing a review, and especially for help on finding the literature to review, sign up for a Personal Research Session .

The specific organization of a literature review depends on the type and purpose of the review, as well as on the specific field or topic being reviewed. But in general, it is a relatively brief but thorough exploration of past and current work on a topic. Rather than a chronological listing of previous work, though, literature reviews are usually organized thematically, such as different theoretical approaches, methodologies, or specific issues or concepts involved in the topic. A thematic organization makes it much easier to examine contrasting perspectives, theoretical approaches, methodologies, findings, etc, and to analyze the strengths and weaknesses of, and point out any gaps in, previous research. And this is the heart of what a literature review is about. A literature review may offer new interpretations, theoretical approaches, or other ideas; if it is part of a research proposal or report it should demonstrate the relationship of the proposed or reported research to others' work; but whatever else it does, it must provide a critical overview of the current state of research efforts. 

Literature reviews are common and very important in the sciences and social sciences. They are less common and have a less important role in the humanities, but they do have a place, especially stand-alone reviews.

Types of Literature Reviews

There are different types of literature reviews, and different purposes for writing a review, but the most common are:

• Stand-alone literature review articles . These provide an overview and analysis of the current state of research on a topic or question. The goal is to evaluate and compare previous research on a topic to provide an analysis of what is currently known, and also to reveal controversies, weaknesses, and gaps in current work, thus pointing to directions for future research. You can find examples published in any number of academic journals, but there is a series of Annual Reviews of *Subject* which are specifically devoted to literature review articles. Writing a stand-alone review is often an effective way to get a good handle on a topic and to develop ideas for your own research program. For example, contrasting theoretical approaches or conflicting interpretations of findings can be the basis of your research project: can you find evidence supporting one interpretation against another, or can you propose an alternative interpretation that overcomes their limitations?
• Part of a research proposal . This could be a proposal for a PhD dissertation, a senior thesis, or a class project. It could also be a submission for a grant. The literature review, by pointing out the current issues and questions concerning a topic, is a crucial part of demonstrating how your proposed research will contribute to the field, and thus of convincing your thesis committee to allow you to pursue the topic of your interest or a funding agency to pay for your research efforts.
• Part of a research report . When you finish your research and write your thesis or paper to present your findings, it should include a literature review to provide the context to which your work is a contribution. Your report, in addition to detailing the methods, results, etc. of your research, should show how your work relates to others' work.

A literature review for a research report is often a revision of the review for a research proposal, which can be a revision of a stand-alone review. Each revision should be a fairly extensive revision. With the increased knowledge of and experience in the topic as you proceed, your understanding of the topic will increase. Thus, you will be in a better position to analyze and critique the literature. In addition, your focus will change as you proceed in your research. Some areas of the literature you initially reviewed will be marginal or irrelevant for your eventual research, and you will need to explore other areas more thoroughly. 

Examples of Literature Reviews

See the series of Annual Reviews of *Subject* which are specifically devoted to literature review articles to find many examples of stand-alone literature reviews in the biomedical, physical, and social sciences. 

Research report articles vary in how they are organized, but a common general structure is to have sections such as:

• Abstract - Brief summary of the contents of the article
• Introduction - A explanation of the purpose of the study, a statement of the research question(s) the study intends to address
• Literature review - A critical assessment of the work done so far on this topic, to show how the current study relates to what has already been done
• Methods - How the study was carried out (e.g. instruments or equipment, procedures, methods to gather and analyze data)
• Results - What was found in the course of the study
• Discussion - What do the results mean
• Conclusion - State the conclusions and implications of the results, and discuss how it relates to the work reviewed in the literature review; also, point to directions for further work in the area

Here are some articles that illustrate variations on this theme. There is no need to read the entire articles (unless the contents interest you); just quickly browse through to see the sections, and see how each section is introduced and what is contained in them.

The Determinants of Undergraduate Grade Point Average: The Relative Importance of Family Background, High School Resources, and Peer Group Effects , in The Journal of Human Resources , v. 34 no. 2 (Spring 1999), p. 268-293.

This article has a standard breakdown of sections:

• Introduction
• Literature Review
• Some discussion sections

First Encounters of the Bureaucratic Kind: Early Freshman Experiences with a Campus Bureaucracy , in The Journal of Higher Education , v. 67 no. 6 (Nov-Dec 1996), p. 660-691.

This one does not have a section specifically labeled as a "literature review" or "review of the literature," but the first few sections cite a long list of other sources discussing previous research in the area before the authors present their own study they are reporting.

• Next: What Is the Literature >>
• Last Updated: Jan 11, 2024 9:48 AM
• URL: https://libguides.wesleyan.edu/litreview

Harvey Cushing/John Hay Whitney Medical Library

• Collections
• Research Help

YSN Doctoral Programs: Steps in Conducting a Literature Review

• Biomedical Databases
• Global (Public Health) Databases
• Soc. Sci., History, and Law Databases
• Grey Literature
• Trials Registers
• Data and Statistics
• Public Policy
• Google Tips
• Recommended Books
• Steps in Conducting a Literature Review

What is a literature review?

A literature review is an integrated analysis -- not just a summary-- of scholarly writings and other relevant evidence related directly to your research question.  That is, it represents a synthesis of the evidence that provides background information on your topic and shows a association between the evidence and your research question.

A literature review may be a stand alone work or the introduction to a larger research paper, depending on the assignment.  Rely heavily on the guidelines your instructor has given you.

Why is it important?

A literature review is important because it:

• Explains the background of research on a topic.
• Demonstrates why a topic is significant to a subject area.
• Discovers relationships between research studies/ideas.
• Identifies major themes, concepts, and researchers on a topic.
• Identifies critical gaps and points of disagreement.
• Discusses further research questions that logically come out of the previous studies.

APA7 Style resources

APA Style Blog - for those harder to find answers

1. Choose a topic. Define your research question.

Your literature review should be guided by your central research question.  The literature represents background and research developments related to a specific research question, interpreted and analyzed by you in a synthesized way.

• Make sure your research question is not too broad or too narrow.  Is it manageable?
• Begin writing down terms that are related to your question. These will be useful for searches later.
• If you have the opportunity, discuss your topic with your professor and your class mates.

2. Decide on the scope of your review

How many studies do you need to look at? How comprehensive should it be? How many years should it cover? 

• This may depend on your assignment.  How many sources does the assignment require?

3. Select the databases you will use to conduct your searches.

Make a list of the databases you will search. 

Where to find databases:

• use the tabs on this guide
• Find other databases in the Nursing Information Resources web page
• More on the Medical Library web page
• ... and more on the Yale University Library web page

4. Conduct your searches to find the evidence. Keep track of your searches.

• Use the key words in your question, as well as synonyms for those words, as terms in your search. Use the database tutorials for help.
• Save the searches in the databases. This saves time when you want to redo, or modify, the searches. It is also helpful to use as a guide is the searches are not finding any useful results.
• Review the abstracts of research studies carefully. This will save you time.
• Use the bibliographies and references of research studies you find to locate others.
• Check with your professor, or a subject expert in the field, if you are missing any key works in the field.
• Ask your librarian for help at any time.
• Use a citation manager, such as EndNote as the repository for your citations. See the EndNote tutorials for help.

Review the literature

Some questions to help you analyze the research:

• What was the research question of the study you are reviewing? What were the authors trying to discover?
• Was the research funded by a source that could influence the findings?
• What were the research methodologies? Analyze its literature review, the samples and variables used, the results, and the conclusions.
• Does the research seem to be complete? Could it have been conducted more soundly? What further questions does it raise?
• If there are conflicting studies, why do you think that is?
• How are the authors viewed in the field? Has this study been cited? If so, how has it been analyzed?

Tips: 

• Review the abstracts carefully.  
• Keep careful notes so that you may track your thought processes during the research process.
• Create a matrix of the studies for easy analysis, and synthesis, across all of the studies.
• << Previous: Recommended Books
• Last Updated: Jan 4, 2024 10:52 AM
• URL: https://guides.library.yale.edu/YSNDoctoral

• Privacy Policy

Buy Me a Coffee

Home » Literature Review – Types Writing Guide and Examples

Literature Review – Types Writing Guide and Examples

Table of Contents

Literature Review

Definition:

A literature review is a comprehensive and critical analysis of the existing literature on a particular topic or research question. It involves identifying, evaluating, and synthesizing relevant literature, including scholarly articles, books, and other sources, to provide a summary and critical assessment of what is known about the topic.

Types of Literature Review

Types of Literature Review are as follows:

• Narrative literature review : This type of review involves a comprehensive summary and critical analysis of the available literature on a particular topic or research question. It is often used as an introductory section of a research paper.
• Systematic literature review: This is a rigorous and structured review that follows a pre-defined protocol to identify, evaluate, and synthesize all relevant studies on a specific research question. It is often used in evidence-based practice and systematic reviews.
• Meta-analysis: This is a quantitative review that uses statistical methods to combine data from multiple studies to derive a summary effect size. It provides a more precise estimate of the overall effect than any individual study.
• Scoping review: This is a preliminary review that aims to map the existing literature on a broad topic area to identify research gaps and areas for further investigation.
• Critical literature review : This type of review evaluates the strengths and weaknesses of the existing literature on a particular topic or research question. It aims to provide a critical analysis of the literature and identify areas where further research is needed.
• Conceptual literature review: This review synthesizes and integrates theories and concepts from multiple sources to provide a new perspective on a particular topic. It aims to provide a theoretical framework for understanding a particular research question.
• Rapid literature review: This is a quick review that provides a snapshot of the current state of knowledge on a specific research question or topic. It is often used when time and resources are limited.
• Thematic literature review : This review identifies and analyzes common themes and patterns across a body of literature on a particular topic. It aims to provide a comprehensive overview of the literature and identify key themes and concepts.
• Realist literature review: This review is often used in social science research and aims to identify how and why certain interventions work in certain contexts. It takes into account the context and complexities of real-world situations.
• State-of-the-art literature review : This type of review provides an overview of the current state of knowledge in a particular field, highlighting the most recent and relevant research. It is often used in fields where knowledge is rapidly evolving, such as technology or medicine.
• Integrative literature review: This type of review synthesizes and integrates findings from multiple studies on a particular topic to identify patterns, themes, and gaps in the literature. It aims to provide a comprehensive understanding of the current state of knowledge on a particular topic.
• Umbrella literature review : This review is used to provide a broad overview of a large and diverse body of literature on a particular topic. It aims to identify common themes and patterns across different areas of research.
• Historical literature review: This type of review examines the historical development of research on a particular topic or research question. It aims to provide a historical context for understanding the current state of knowledge on a particular topic.
• Problem-oriented literature review : This review focuses on a specific problem or issue and examines the literature to identify potential solutions or interventions. It aims to provide practical recommendations for addressing a particular problem or issue.
• Mixed-methods literature review : This type of review combines quantitative and qualitative methods to synthesize and analyze the available literature on a particular topic. It aims to provide a more comprehensive understanding of the research question by combining different types of evidence.

Parts of Literature Review

Parts of a literature review are as follows:

Introduction

The introduction of a literature review typically provides background information on the research topic and why it is important. It outlines the objectives of the review, the research question or hypothesis, and the scope of the review.

Literature Search

This section outlines the search strategy and databases used to identify relevant literature. The search terms used, inclusion and exclusion criteria, and any limitations of the search are described.

Literature Analysis

The literature analysis is the main body of the literature review. This section summarizes and synthesizes the literature that is relevant to the research question or hypothesis. The review should be organized thematically, chronologically, or by methodology, depending on the research objectives.

Critical Evaluation

Critical evaluation involves assessing the quality and validity of the literature. This includes evaluating the reliability and validity of the studies reviewed, the methodology used, and the strength of the evidence.

The conclusion of the literature review should summarize the main findings, identify any gaps in the literature, and suggest areas for future research. It should also reiterate the importance of the research question or hypothesis and the contribution of the literature review to the overall research project.

The references list includes all the sources cited in the literature review, and follows a specific referencing style (e.g., APA, MLA, Harvard).

How to write Literature Review

Here are some steps to follow when writing a literature review:

• Define your research question or topic : Before starting your literature review, it is essential to define your research question or topic. This will help you identify relevant literature and determine the scope of your review.
• Conduct a comprehensive search: Use databases and search engines to find relevant literature. Look for peer-reviewed articles, books, and other academic sources that are relevant to your research question or topic.
• Evaluate the sources: Once you have found potential sources, evaluate them critically to determine their relevance, credibility, and quality. Look for recent publications, reputable authors, and reliable sources of data and evidence.
• Organize your sources: Group the sources by theme, method, or research question. This will help you identify similarities and differences among the literature, and provide a structure for your literature review.
• Analyze and synthesize the literature : Analyze each source in depth, identifying the key findings, methodologies, and conclusions. Then, synthesize the information from the sources, identifying patterns and themes in the literature.
• Write the literature review : Start with an introduction that provides an overview of the topic and the purpose of the literature review. Then, organize the literature according to your chosen structure, and analyze and synthesize the sources. Finally, provide a conclusion that summarizes the key findings of the literature review, identifies gaps in knowledge, and suggests areas for future research.
• Edit and proofread: Once you have written your literature review, edit and proofread it carefully to ensure that it is well-organized, clear, and concise.

Examples of Literature Review

Here’s an example of how a literature review can be conducted for a thesis on the topic of “ The Impact of Social Media on Teenagers’ Mental Health”:

• Start by identifying the key terms related to your research topic. In this case, the key terms are “social media,” “teenagers,” and “mental health.”
• Use academic databases like Google Scholar, JSTOR, or PubMed to search for relevant articles, books, and other publications. Use these keywords in your search to narrow down your results.
• Evaluate the sources you find to determine if they are relevant to your research question. You may want to consider the publication date, author’s credentials, and the journal or book publisher.
• Begin reading and taking notes on each source, paying attention to key findings, methodologies used, and any gaps in the research.
• Organize your findings into themes or categories. For example, you might categorize your sources into those that examine the impact of social media on self-esteem, those that explore the effects of cyberbullying, and those that investigate the relationship between social media use and depression.
• Synthesize your findings by summarizing the key themes and highlighting any gaps or inconsistencies in the research. Identify areas where further research is needed.
• Use your literature review to inform your research questions and hypotheses for your thesis.

For example, after conducting a literature review on the impact of social media on teenagers’ mental health, a thesis might look like this:

“Using a mixed-methods approach, this study aims to investigate the relationship between social media use and mental health outcomes in teenagers. Specifically, the study will examine the effects of cyberbullying, social comparison, and excessive social media use on self-esteem, anxiety, and depression. Through an analysis of survey data and qualitative interviews with teenagers, the study will provide insight into the complex relationship between social media use and mental health outcomes, and identify strategies for promoting positive mental health outcomes in young people.”

Reference: Smith, J., Jones, M., & Lee, S. (2019). The effects of social media use on adolescent mental health: A systematic review. Journal of Adolescent Health, 65(2), 154-165. doi:10.1016/j.jadohealth.2019.03.024

Reference Example: Author, A. A., Author, B. B., & Author, C. C. (Year). Title of article. Title of Journal, volume number(issue number), page range. doi:0000000/000000000000 or URL

Applications of Literature Review

some applications of literature review in different fields:

• Social Sciences: In social sciences, literature reviews are used to identify gaps in existing research, to develop research questions, and to provide a theoretical framework for research. Literature reviews are commonly used in fields such as sociology, psychology, anthropology, and political science.
• Natural Sciences: In natural sciences, literature reviews are used to summarize and evaluate the current state of knowledge in a particular field or subfield. Literature reviews can help researchers identify areas where more research is needed and provide insights into the latest developments in a particular field. Fields such as biology, chemistry, and physics commonly use literature reviews.
• Health Sciences: In health sciences, literature reviews are used to evaluate the effectiveness of treatments, identify best practices, and determine areas where more research is needed. Literature reviews are commonly used in fields such as medicine, nursing, and public health.
• Humanities: In humanities, literature reviews are used to identify gaps in existing knowledge, develop new interpretations of texts or cultural artifacts, and provide a theoretical framework for research. Literature reviews are commonly used in fields such as history, literary studies, and philosophy.

Role of Literature Review in Research

Here are some applications of literature review in research:

• Identifying Research Gaps : Literature review helps researchers identify gaps in existing research and literature related to their research question. This allows them to develop new research questions and hypotheses to fill those gaps.
• Developing Theoretical Framework: Literature review helps researchers develop a theoretical framework for their research. By analyzing and synthesizing existing literature, researchers can identify the key concepts, theories, and models that are relevant to their research.
• Selecting Research Methods : Literature review helps researchers select appropriate research methods and techniques based on previous research. It also helps researchers to identify potential biases or limitations of certain methods and techniques.
• Data Collection and Analysis: Literature review helps researchers in data collection and analysis by providing a foundation for the development of data collection instruments and methods. It also helps researchers to identify relevant data sources and identify potential data analysis techniques.
• Communicating Results: Literature review helps researchers to communicate their results effectively by providing a context for their research. It also helps to justify the significance of their findings in relation to existing research and literature.

Purpose of Literature Review

Some of the specific purposes of a literature review are as follows:

• To provide context: A literature review helps to provide context for your research by situating it within the broader body of literature on the topic.
• To identify gaps and inconsistencies: A literature review helps to identify areas where further research is needed or where there are inconsistencies in the existing literature.
• To synthesize information: A literature review helps to synthesize the information from multiple sources and present a coherent and comprehensive picture of the current state of knowledge on the topic.
• To identify key concepts and theories : A literature review helps to identify key concepts and theories that are relevant to your research question and provide a theoretical framework for your study.
• To inform research design: A literature review can inform the design of your research study by identifying appropriate research methods, data sources, and research questions.

Characteristics of Literature Review

Some Characteristics of Literature Review are as follows:

• Identifying gaps in knowledge: A literature review helps to identify gaps in the existing knowledge and research on a specific topic or research question. By analyzing and synthesizing the literature, you can identify areas where further research is needed and where new insights can be gained.
• Establishing the significance of your research: A literature review helps to establish the significance of your own research by placing it in the context of existing research. By demonstrating the relevance of your research to the existing literature, you can establish its importance and value.
• Informing research design and methodology : A literature review helps to inform research design and methodology by identifying the most appropriate research methods, techniques, and instruments. By reviewing the literature, you can identify the strengths and limitations of different research methods and techniques, and select the most appropriate ones for your own research.
• Supporting arguments and claims: A literature review provides evidence to support arguments and claims made in academic writing. By citing and analyzing the literature, you can provide a solid foundation for your own arguments and claims.
• I dentifying potential collaborators and mentors: A literature review can help identify potential collaborators and mentors by identifying researchers and practitioners who are working on related topics or using similar methods. By building relationships with these individuals, you can gain valuable insights and support for your own research and practice.
• Keeping up-to-date with the latest research : A literature review helps to keep you up-to-date with the latest research on a specific topic or research question. By regularly reviewing the literature, you can stay informed about the latest findings and developments in your field.

Advantages of Literature Review

There are several advantages to conducting a literature review as part of a research project, including:

• Establishing the significance of the research : A literature review helps to establish the significance of the research by demonstrating the gap or problem in the existing literature that the study aims to address.
• Identifying key concepts and theories: A literature review can help to identify key concepts and theories that are relevant to the research question, and provide a theoretical framework for the study.
• Supporting the research methodology : A literature review can inform the research methodology by identifying appropriate research methods, data sources, and research questions.
• Providing a comprehensive overview of the literature : A literature review provides a comprehensive overview of the current state of knowledge on a topic, allowing the researcher to identify key themes, debates, and areas of agreement or disagreement.
• Identifying potential research questions: A literature review can help to identify potential research questions and areas for further investigation.
• Avoiding duplication of research: A literature review can help to avoid duplication of research by identifying what has already been done on a topic, and what remains to be done.
• Enhancing the credibility of the research : A literature review helps to enhance the credibility of the research by demonstrating the researcher’s knowledge of the existing literature and their ability to situate their research within a broader context.

Limitations of Literature Review

Limitations of Literature Review are as follows:

• Limited scope : Literature reviews can only cover the existing literature on a particular topic, which may be limited in scope or depth.
• Publication bias : Literature reviews may be influenced by publication bias, which occurs when researchers are more likely to publish positive results than negative ones. This can lead to an incomplete or biased picture of the literature.
• Quality of sources : The quality of the literature reviewed can vary widely, and not all sources may be reliable or valid.
• Time-limited: Literature reviews can become quickly outdated as new research is published, making it difficult to keep up with the latest developments in a field.
• Subjective interpretation : Literature reviews can be subjective, and the interpretation of the findings can vary depending on the researcher’s perspective or bias.
• Lack of original data : Literature reviews do not generate new data, but rather rely on the analysis of existing studies.
• Risk of plagiarism: It is important to ensure that literature reviews do not inadvertently contain plagiarism, which can occur when researchers use the work of others without proper attribution.

About the author

Muhammad Hassan

Researcher, Academic Writer, Web developer

You may also like

Data Collection – Methods Types and Examples

Delimitations in Research – Types, Examples and...

Research Process – Steps, Examples and Tips

Research Design – Types, Methods and Examples

Institutional Review Board – Application Sample...

Evaluating Research – Process, Examples and...

• Search This Site All UCSD Sites Faculty/Staff Search Term
• Contact & Directions
• Climate Statement
• Cognitive Behavioral Neuroscience
• Cognitive Psychology
• Developmental Psychology
• Social Psychology
• Adjunct Faculty
• Non-Senate Instructors
• Researchers
• Psychology Grads
• Affiliated Grads
• New and Prospective Students
• Honors Program
• Experiential Learning
• Programs & Events
• Psi Chi / Psychology Club
• Prospective PhD Students
• Current PhD Students
• Area Brown Bags
• Colloquium Series
• Anderson Distinguished Lecture Series
• Speaker Videos
• Undergraduate Program
• Academic and Writing Resources

Writing Research Papers

• Writing a Literature Review

When writing a research paper on a specific topic, you will often need to include an overview of any prior research that has been conducted on that topic.  For example, if your research paper is describing an experiment on fear conditioning, then you will probably need to provide an overview of prior research on fear conditioning.  That overview is typically known as a literature review.  

Please note that a full-length literature review article may be suitable for fulfilling the requirements for the Psychology B.S. Degree Research Paper .  For further details, please check with your faculty advisor.

Different Types of Literature Reviews

Literature reviews come in many forms.  They can be part of a research paper, for example as part of the Introduction section.  They can be one chapter of a doctoral dissertation.  Literature reviews can also “stand alone” as separate articles by themselves.  For instance, some journals such as Annual Review of Psychology , Psychological Bulletin , and others typically publish full-length review articles.  Similarly, in courses at UCSD, you may be asked to write a research paper that is itself a literature review (such as, with an instructor’s permission, in fulfillment of the B.S. Degree Research Paper requirement). Alternatively, you may be expected to include a literature review as part of a larger research paper (such as part of an Honors Thesis). 

Literature reviews can be written using a variety of different styles.  These may differ in the way prior research is reviewed as well as the way in which the literature review is organized.  Examples of stylistic variations in literature reviews include: 

• Summarization of prior work vs. critical evaluation. In some cases, prior research is simply described and summarized; in other cases, the writer compares, contrasts, and may even critique prior research (for example, discusses their strengths and weaknesses).
• Chronological vs. categorical and other types of organization. In some cases, the literature review begins with the oldest research and advances until it concludes with the latest research.  In other cases, research is discussed by category (such as in groupings of closely related studies) without regard for chronological order.  In yet other cases, research is discussed in terms of opposing views (such as when different research studies or researchers disagree with one another).

Overall, all literature reviews, whether they are written as a part of a larger work or as separate articles unto themselves, have a common feature: they do not present new research; rather, they provide an overview of prior research on a specific topic . 

How to Write a Literature Review

When writing a literature review, it can be helpful to rely on the following steps.  Please note that these procedures are not necessarily only for writing a literature review that becomes part of a larger article; they can also be used for writing a full-length article that is itself a literature review (although such reviews are typically more detailed and exhaustive; for more information please refer to the Further Resources section of this page).

Steps for Writing a Literature Review

1. Identify and define the topic that you will be reviewing.

The topic, which is commonly a research question (or problem) of some kind, needs to be identified and defined as clearly as possible.  You need to have an idea of what you will be reviewing in order to effectively search for references and to write a coherent summary of the research on it.  At this stage it can be helpful to write down a description of the research question, area, or topic that you will be reviewing, as well as to identify any keywords that you will be using to search for relevant research.

2. Conduct a literature search.

Use a range of keywords to search databases such as PsycINFO and any others that may contain relevant articles.  You should focus on peer-reviewed, scholarly articles.  Published books may also be helpful, but keep in mind that peer-reviewed articles are widely considered to be the “gold standard” of scientific research.  Read through titles and abstracts, select and obtain articles (that is, download, copy, or print them out), and save your searches as needed.  For more information about this step, please see the Using Databases and Finding Scholarly References section of this website.

3. Read through the research that you have found and take notes.

Absorb as much information as you can.  Read through the articles and books that you have found, and as you do, take notes.  The notes should include anything that will be helpful in advancing your own thinking about the topic and in helping you write the literature review (such as key points, ideas, or even page numbers that index key information).  Some references may turn out to be more helpful than others; you may notice patterns or striking contrasts between different sources ; and some sources may refer to yet other sources of potential interest.  This is often the most time-consuming part of the review process.  However, it is also where you get to learn about the topic in great detail.  For more details about taking notes, please see the “Reading Sources and Taking Notes” section of the Finding Scholarly References page of this website.

4. Organize your notes and thoughts; create an outline.

At this stage, you are close to writing the review itself.  However, it is often helpful to first reflect on all the reading that you have done.  What patterns stand out?  Do the different sources converge on a consensus?  Or not?  What unresolved questions still remain?  You should look over your notes (it may also be helpful to reorganize them), and as you do, to think about how you will present this research in your literature review.  Are you going to summarize or critically evaluate?  Are you going to use a chronological or other type of organizational structure?  It can also be helpful to create an outline of how your literature review will be structured.

5. Write the literature review itself and edit and revise as needed.

The final stage involves writing.  When writing, keep in mind that literature reviews are generally characterized by a summary style in which prior research is described sufficiently to explain critical findings but does not include a high level of detail (if readers want to learn about all the specific details of a study, then they can look up the references that you cite and read the original articles themselves).  However, the degree of emphasis that is given to individual studies may vary (more or less detail may be warranted depending on how critical or unique a given study was).   After you have written a first draft, you should read it carefully and then edit and revise as needed.  You may need to repeat this process more than once.  It may be helpful to have another person read through your draft(s) and provide feedback.

6. Incorporate the literature review into your research paper draft.

After the literature review is complete, you should incorporate it into your research paper (if you are writing the review as one component of a larger paper).  Depending on the stage at which your paper is at, this may involve merging your literature review into a partially complete Introduction section, writing the rest of the paper around the literature review, or other processes.

Further Tips for Writing a Literature Review

Full-length literature reviews

• Many full-length literature review articles use a three-part structure: Introduction (where the topic is identified and any trends or major problems in the literature are introduced), Body (where the studies that comprise the literature on that topic are discussed), and Discussion or Conclusion (where major patterns and points are discussed and the general state of what is known about the topic is summarized)

Literature reviews as part of a larger paper

• An “express method” of writing a literature review for a research paper is as follows: first, write a one paragraph description of each article that you read. Second, choose how you will order all the paragraphs and combine them in one document.  Third, add transitions between the paragraphs, as well as an introductory and concluding paragraph. 1
• A literature review that is part of a larger research paper typically does not have to be exhaustive. Rather, it should contain most or all of the significant studies about a research topic but not tangential or loosely related ones. 2   Generally, literature reviews should be sufficient for the reader to understand the major issues and key findings about a research topic.  You may however need to confer with your instructor or editor to determine how comprehensive you need to be.

Benefits of Literature Reviews

By summarizing prior research on a topic, literature reviews have multiple benefits.  These include:

• Literature reviews help readers understand what is known about a topic without having to find and read through multiple sources.
• Literature reviews help “set the stage” for later reading about new research on a given topic (such as if they are placed in the Introduction of a larger research paper). In other words, they provide helpful background and context.
• Literature reviews can also help the writer learn about a given topic while in the process of preparing the review itself. In the act of research and writing the literature review, the writer gains expertise on the topic .

Downloadable Resources

• How to Write APA Style Research Papers (a comprehensive guide) [ PDF ]
• Tips for Writing APA Style Research Papers (a brief summary) [ PDF ]
• Example APA Style Research Paper (for B.S. Degree – literature review) [ PDF ]

Further Resources

How-To Videos     

• Writing Research Paper Videos
• UCSD Library Psychology Research Guide: Literature Reviews

External Resources

• Developing and Writing a Literature Review from N Carolina A&T State University
• Example of a Short Literature Review from York College CUNY
• How to Write a Review of Literature from UW-Madison
• Writing a Literature Review from UC Santa Cruz  
• Pautasso, M. (2013). Ten Simple Rules for Writing a Literature Review. PLoS Computational Biology, 9 (7), e1003149. doi : 1371/journal.pcbi.1003149

1 Ashton, W. Writing a short literature review . [PDF]     

2 carver, l. (2014).  writing the research paper [workshop]. , prepared by s. c. pan for ucsd psychology.

Back to top

• Research Paper Structure
• Formatting Research Papers
• Using Databases and Finding References
• What Types of References Are Appropriate?
• Evaluating References and Taking Notes
• Citing References
• Writing Process and Revising
• Improving Scientific Writing
• Academic Integrity and Avoiding Plagiarism
• Writing Research Papers Videos

• UWF Libraries

Literature Review: Conducting & Writing

• Sample Literature Reviews
• Steps for Conducting a Lit Review
• Finding "The Literature"
• Organizing/Writing
• APA Style This link opens in a new window
• Chicago: Notes Bibliography This link opens in a new window
• MLA Style This link opens in a new window

Sample Lit Reviews from Communication Arts

Have an exemplary literature review.

• Literature Review Sample 1
• Literature Review Sample 2
• Literature Review Sample 3

Have you written a stellar literature review you care to share for teaching purposes?

Are you an instructor who has received an exemplary literature review and have permission from the student to post?

Please contact Britt McGowan at [email protected] for inclusion in this guide. All disciplines welcome and encouraged.

• << Previous: MLA Style
• Next: Get Help! >>
• Last Updated: Mar 22, 2024 9:37 AM
• URL: https://libguides.uwf.edu/litreview

Want to create or adapt books like this? Learn more about how Pressbooks supports open publishing practices.

What is a Literature Review?

What’s a literature review.

The straightforward answer is that a literature review is a review or synthesis of all the research published on a certain topic. But I’d rather explain it from a skateboarder’s perspective:

One of my favorite movies is the 1989 classic Back to the Future Part 2 where the bodacious skater Marty McFly time-travels to the future and sees a hoverboard. As a kid, I was a dabbling skateboarder and thought if I could just have one of those hoverboards, all my troubles would disappear. It was an optimistic time.

Trouble is, hoverboards are really hard to make. We’ve already passed the year 2015 when the “Future” of Back to the Future Part 2 takes place, and guess what? No hoverboards. I know you’ve seen a skateboard-like, two-wheeled device marketed with the name “Hoverboard” but that’s just an electric, no-handled scooter.

I want a real hoverboard. That you ride in the air . So how can we know when real hoverboards will be available? How can we know where the technology is now? Will we know a real hoverboard when we see one? Tony Hawk, the best skateboarder of all time (whose face was incidentally taped to my wall in the ’80s) recently filmed a 2-minute video of how far real hoverboard technology has come–filmed on the very day Marty McFly supposedly went to the future: October 21, 2015:

Tony Hawk and the cutting edge of hoverboard research

Although this “hoverboard” was really a huge black rectangle the size of Delaware floating only an inch off the ground, and although Tony Hawk fell off a lot, he was technically in the air, so I’m taking that as a good sign. Then recently, a professional jet ski rider broke the world record for longest time “hovering” in the air with a highly dangerous jet-engine-propelled contraption called Flyboard Air. It’s also definitely a step in the right direction, but there’s a big problem (beside extreme danger): it’s projected to cost around $250,000.

The good news is, now we’ve found the point where hoverboard research actually is. The bad news: we have to face the sad truth that it might still be a while before we get real flying hoverboards. But at least now we know.

The State of a Field on a Topic

That leads me to literature reviews. Whenever you want to know the state of a field of research like how far hoverboard technology has come, the best way to find out is probably not YouTube videos. It turns out you can do something much more reliable: conduct a literature review . In this case, “literature” doesn’t mean the Victorian novels you read in English class, it means all the research published on a certain topic. So a literature review is simply a review or a synthesis of the research published on a topic.

Researchers today don’t just start projects out of the blue–they do their homework first by finding out what others have already researched. So if you want to make a hoverboard, you don’t just go to Home Depot and buy random parts–you research what others have done and check out the conversation so you don’t have to reinvent the wheel.

“If I have seen further, it is by standing on the shoulders of giants.” –Sir Isaac Newton (and the motto of Google Scholar)

Before good researchers set up any surveys or experiments, or even write a proposal for funding, they figure out exactly which research questions have already been asked and answered. Same goes for anyone wanting to make a product that will sell. But more importantly, they look for the gaps in the research where answers have yet to be found. And then they focus their own research on filling in some of those gaps. That’ll be your job, too.

In other words, the goal of a literature review is to find the sweet spot where the most promising research is happening now–we call that the cutting edge.

How is a Literature Review different from a typical Research Paper?

You’ve probably been writing research papers most of your life– starting from the five-paragraph essay you learned in high school to the term paper you wrote last semester that had a thesis statement and lots of quotes. So it can seem daunting to switch gears to writing a literature review, but there are some distinct advantages to making the switch. The trick is first understanding the difference between the two.

Research Papers are Thesis Driven

The difference between a typical research paper and a literature review is your purpose and strategy. When you’re assigned to write a research paper, you start with a thesis or argument that you’d like to make. Your thesis has to do with changes you’d like to see in the future. Then you search for sources that support your point. You might adjust your thesis if you come across sources that challenge your claim, but generally, the sources you’ve gathered become evidence for your thesis and you use them to support your point. In other words, your argumentative research paper is driven by your thesis .

Literature Reviews are Source Driven

In contrast, when you write a Literature Review, the sources themselves dictate what you’ll say in your paper. Remember, your goal is to tell your audience the state of the field on a topic–what’s been happening in the published research–so you can find the cutting edge and where the research gaps are. Therefore, you need to find and evaluate the most relevant sources surrounding a topic and then write a review based on what you find . You can’t decide on a thesis statement or know what points you’ll make before you start because you have to find out what researchers are doing before you can report on that. Simply put, your literature review is driven by your sources .

You’ll still have an overarching point/thesis that controls your literature review paper structure, but it will be a claim about what patterns you found in the research– not an argument about a change you want to see in the future or a new way to look at something. And you’ll decide on your thesis much later in the writing process. Here’s a table that compares the writing process of a traditional research paper with that of a literature review:

Literature Reviews: Catching up with Old Friends

What do you do when you meet an old friend? You ask,

“How are you? What have you been up to? Fill me in!”

Literature Reviews are like getting filled in by an old friend . Only this time, you’re explaining how a field of research has gotten to the present (like how far hoverboard technology has come). But like a conversation with an old friend, you want to review only the details most relevant to the situation. You don’t usually give a moment-by-moment chronology of what you’ve done in your life (no one has time for that); rather, you talk in terms of categories–work, family, travel, etc. This is like the synthesis that happens in a Literature Review. As you read sources about a specific topic, you’ll look for themes, for similarities and differences, for points of agreement and disagreement, for gaps in the research that haven’t been filled in yet. Those themes become the categories you’ll talk about in your literature review so your audience will understand the big picture about your topic.

Literature Reviews in the Sciences

Grant proposals.

Any grant proposal submitted to request research funding begins with an extensive literature review to justify the need for the research funds. If you can prove there’s a gap in knowledge, it makes it that much easier to convince your audience to give you funding to fill that gap.

IMRAD Articles

The Introduction of an IMRAD article includes a literature review. Photo by Tom Toyosak i on Wikimedia Commons

IMRAD (pronounced “im-rad”) stands for Introduction, Methods, Results, and Discussion and is the most common genre published in the social sciences and sciences. Most of the sources you gather will likely be IMRAD-format papers. The I in IMRAD stands for Introduction and usually consists of a review of the literature on the authors’ research topic. The author(s) usually use the Introduction section to report on the published literature about their research topic and reveal the trends and gaps in current research. An added benefit to beginning an article this way is that by showing the gaps in the research, the author(s) can justify their own research and explain the significance of the topic they chose to examine. Clever!

As you might guess, the sections following the Introduction (Methods, Results, Discussion) describe the primary research the author(s) conducted to answer their research question. First they report on their quantitative and/or qualitative M ethods (M in IMRAD) including statistical analyses. Then they publish their R esults (R in IMRAD). Finally, the author(s) embark on a D iscussion (D in IMRAD) of their results in the context of the greater field of research and make suggestions for future research. This starts the research cycle over again as someone else reads their article as part of their own review of the literature and discovers a gap in the research that can be filled by new primary research. 

Published Literature Reviews

In the world of science and social science, literature reviews can also be published on their own. For example, if someone does an extensive investigation into an important topic, the publishers of academic journals will often publish that literature review on its own to help other researchers understand that topic better.

Popular Literature Reviews

Lest you think nerdy academics are the only ones who rely on literature reviews, recall the last time you went on Wikipedia . If you think about it, Wikipedia is really just a giant literature review on millions of topics. Although the information on Wikipedia is not formally peer-reviewed like the reviews published in academic journals, they do cite all their sources and frequently revise to keep the information current. Clearly there’s a market for relevant information. If you really want your mind to explode Inception -style, look up “Wikipedia” on Wikipedia and you’ll find a literature review about a literature review.

Adapted from “What is a Literature Review?” in Writing in the Social Sciences. Authored by Christie Cowles Charles. Located at: https://edtechbooks.org/writing.

License: CC BY- SA

What is a Literature Review? Copyright © 2020 by Sara Rufner is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License , except where otherwise noted.

Share This Book

Log in using your username and password

• Search More Search for this keyword Advanced search
• Latest content
• Current issue
• Write for Us
• BMJ Journals More You are viewing from: Google Indexer

You are here

• Volume 24, Issue 2
• Five tips for developing useful literature summary tables for writing review articles
• Article Text
• Article info
• Citation Tools
• Rapid Responses
• Article metrics

• http://orcid.org/0000-0003-0157-5319 Ahtisham Younas 1 , 2 ,
• http://orcid.org/0000-0002-7839-8130 Parveen Ali 3 , 4
• 1 Memorial University of Newfoundland , St John's , Newfoundland , Canada
• 2 Swat College of Nursing , Pakistan
• 3 School of Nursing and Midwifery , University of Sheffield , Sheffield , South Yorkshire , UK
• 4 Sheffield University Interpersonal Violence Research Group , Sheffield University , Sheffield , UK
• Correspondence to Ahtisham Younas, Memorial University of Newfoundland, St John's, NL A1C 5C4, Canada; ay6133{at}mun.ca

https://doi.org/10.1136/ebnurs-2021-103417

Statistics from Altmetric.com

Request permissions.

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

Introduction

Literature reviews offer a critical synthesis of empirical and theoretical literature to assess the strength of evidence, develop guidelines for practice and policymaking, and identify areas for future research. 1 It is often essential and usually the first task in any research endeavour, particularly in masters or doctoral level education. For effective data extraction and rigorous synthesis in reviews, the use of literature summary tables is of utmost importance. A literature summary table provides a synopsis of an included article. It succinctly presents its purpose, methods, findings and other relevant information pertinent to the review. The aim of developing these literature summary tables is to provide the reader with the information at one glance. Since there are multiple types of reviews (eg, systematic, integrative, scoping, critical and mixed methods) with distinct purposes and techniques, 2 there could be various approaches for developing literature summary tables making it a complex task specialty for the novice researchers or reviewers. Here, we offer five tips for authors of the review articles, relevant to all types of reviews, for creating useful and relevant literature summary tables. We also provide examples from our published reviews to illustrate how useful literature summary tables can be developed and what sort of information should be provided.

Tip 1: provide detailed information about frameworks and methods

• Download figure
• Open in new tab
• Download powerpoint

Tabular literature summaries from a scoping review. Source: Rasheed et al . 3

The provision of information about conceptual and theoretical frameworks and methods is useful for several reasons. First, in quantitative (reviews synthesising the results of quantitative studies) and mixed reviews (reviews synthesising the results of both qualitative and quantitative studies to address a mixed review question), it allows the readers to assess the congruence of the core findings and methods with the adapted framework and tested assumptions. In qualitative reviews (reviews synthesising results of qualitative studies), this information is beneficial for readers to recognise the underlying philosophical and paradigmatic stance of the authors of the included articles. For example, imagine the authors of an article, included in a review, used phenomenological inquiry for their research. In that case, the review authors and the readers of the review need to know what kind of (transcendental or hermeneutic) philosophical stance guided the inquiry. Review authors should, therefore, include the philosophical stance in their literature summary for the particular article. Second, information about frameworks and methods enables review authors and readers to judge the quality of the research, which allows for discerning the strengths and limitations of the article. For example, if authors of an included article intended to develop a new scale and test its psychometric properties. To achieve this aim, they used a convenience sample of 150 participants and performed exploratory (EFA) and confirmatory factor analysis (CFA) on the same sample. Such an approach would indicate a flawed methodology because EFA and CFA should not be conducted on the same sample. The review authors must include this information in their summary table. Omitting this information from a summary could lead to the inclusion of a flawed article in the review, thereby jeopardising the review’s rigour.

Tip 2: include strengths and limitations for each article

Critical appraisal of individual articles included in a review is crucial for increasing the rigour of the review. Despite using various templates for critical appraisal, authors often do not provide detailed information about each reviewed article’s strengths and limitations. Merely noting the quality score based on standardised critical appraisal templates is not adequate because the readers should be able to identify the reasons for assigning a weak or moderate rating. Many recent critical appraisal checklists (eg, Mixed Methods Appraisal Tool) discourage review authors from assigning a quality score and recommend noting the main strengths and limitations of included studies. It is also vital that methodological and conceptual limitations and strengths of the articles included in the review are provided because not all review articles include empirical research papers. Rather some review synthesises the theoretical aspects of articles. Providing information about conceptual limitations is also important for readers to judge the quality of foundations of the research. For example, if you included a mixed-methods study in the review, reporting the methodological and conceptual limitations about ‘integration’ is critical for evaluating the study’s strength. Suppose the authors only collected qualitative and quantitative data and did not state the intent and timing of integration. In that case, the strength of the study is weak. Integration only occurred at the levels of data collection. However, integration may not have occurred at the analysis, interpretation and reporting levels.

Tip 3: write conceptual contribution of each reviewed article

While reading and evaluating review papers, we have observed that many review authors only provide core results of the article included in a review and do not explain the conceptual contribution offered by the included article. We refer to conceptual contribution as a description of how the article’s key results contribute towards the development of potential codes, themes or subthemes, or emerging patterns that are reported as the review findings. For example, the authors of a review article noted that one of the research articles included in their review demonstrated the usefulness of case studies and reflective logs as strategies for fostering compassion in nursing students. The conceptual contribution of this research article could be that experiential learning is one way to teach compassion to nursing students, as supported by case studies and reflective logs. This conceptual contribution of the article should be mentioned in the literature summary table. Delineating each reviewed article’s conceptual contribution is particularly beneficial in qualitative reviews, mixed-methods reviews, and critical reviews that often focus on developing models and describing or explaining various phenomena. Figure 2 offers an example of a literature summary table. 4

Tabular literature summaries from a critical review. Source: Younas and Maddigan. 4

Tip 4: compose potential themes from each article during summary writing

While developing literature summary tables, many authors use themes or subthemes reported in the given articles as the key results of their own review. Such an approach prevents the review authors from understanding the article’s conceptual contribution, developing rigorous synthesis and drawing reasonable interpretations of results from an individual article. Ultimately, it affects the generation of novel review findings. For example, one of the articles about women’s healthcare-seeking behaviours in developing countries reported a theme ‘social-cultural determinants of health as precursors of delays’. Instead of using this theme as one of the review findings, the reviewers should read and interpret beyond the given description in an article, compare and contrast themes, findings from one article with findings and themes from another article to find similarities and differences and to understand and explain bigger picture for their readers. Therefore, while developing literature summary tables, think twice before using the predeveloped themes. Including your themes in the summary tables (see figure 1 ) demonstrates to the readers that a robust method of data extraction and synthesis has been followed.

Tip 5: create your personalised template for literature summaries

Often templates are available for data extraction and development of literature summary tables. The available templates may be in the form of a table, chart or a structured framework that extracts some essential information about every article. The commonly used information may include authors, purpose, methods, key results and quality scores. While extracting all relevant information is important, such templates should be tailored to meet the needs of the individuals’ review. For example, for a review about the effectiveness of healthcare interventions, a literature summary table must include information about the intervention, its type, content timing, duration, setting, effectiveness, negative consequences, and receivers and implementers’ experiences of its usage. Similarly, literature summary tables for articles included in a meta-synthesis must include information about the participants’ characteristics, research context and conceptual contribution of each reviewed article so as to help the reader make an informed decision about the usefulness or lack of usefulness of the individual article in the review and the whole review.

In conclusion, narrative or systematic reviews are almost always conducted as a part of any educational project (thesis or dissertation) or academic or clinical research. Literature reviews are the foundation of research on a given topic. Robust and high-quality reviews play an instrumental role in guiding research, practice and policymaking. However, the quality of reviews is also contingent on rigorous data extraction and synthesis, which require developing literature summaries. We have outlined five tips that could enhance the quality of the data extraction and synthesis process by developing useful literature summaries.

• Aromataris E ,
• Rasheed SP ,

Twitter @Ahtisham04, @parveenazamali

Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

Competing interests None declared.

Patient consent for publication Not required.

Provenance and peer review Not commissioned; externally peer reviewed.

Read the full text or download the PDF:

AI-Based Research Tools

Your librarian.

Introduction: Conducting AI Powered Research

AI tools for research can help you to discover new sources for your research assignment or literature review! These tools will synthesize information from large databases of scholarly output with the aim of finding the most relevant articles, thereby saving researchers' time. As with our research databases or any other search tool, however, it's important to:

1) always evaluate results/output;

2) not rely on any one tool for all of your research,

as you will risk missing important information on your topic of interest. 

As always, if you have questions about using these tools for your research, please contact your friendly Rider librarian!

Disclaimer:  Rider University Libraries do not have subscription access to the AI-powered tools listed below. The guide serves solely as an informational resource. It is recommended that you assess these tools and their usage methodologies independently. 

• ELICIT IS AN "AI-POWERED RESEARCH ASSISTANT" - useful for finding papers, filtering study types, automating research flow, brainstorming, summarizing and more.
• Elicit is a research assistant using language models like GPT-3 to automate parts of researchers' workflows.
• Currently, the main workflow in Elicit is Literature Review--if you ask a question, Elicit will show relevant papers and summaries of key information about those papers in an easy-to-use table. 
• Access the Elicit FAQ here.

Research Rabbit

• RESEARCH RABBIT IS A CITATION-BASED MAPPING TOOL that focuses on the relationships between research works. 
• Bills itself as the "Spotify for Papers" !
• It uses visualizations to help researchers find similar papers and locate other researchers in their field. 
• Research Rabbit uses multiple databases, but does not name them (more information can be found on the FAQ page).
• Keep up with the latest research related to your collections using the "Personalized Digests" feature.

• PERPLEXITY   IS A SEARCH ENGINE THAT SEARCHES  Large Language Models (LLMs) to provide AI-generated answers (much like ChatGPT)
• Billed as "an alternative to traditional search engines, where you can directly pose your questions and receive concise, accurate answers backed up by a curated set of sources."
• It has a conversational interface, "contextual awareness" and "personalization" to learn your interests and preferences over time. 
• Using an "advanced search engine, it processes your questions and tasks it then uses predictive text capabilities to generate useful responses, choosing the best one from multiple sources, and summarizes the results in a concise way."
• Access the Perplexity FAQ here.

• CONSENSUS  USES LARGE LANGUAGE MODELS  (like Elicit) to help researchers find and synthesize answers to research questions, focusing on scholarly authors' findings and claims in each paper.
• Bills itself as the "ChatGPT of research!"--simply type in your research questions and off you go!
• Consensus provides helpful guidance on question prompts for different question types.
• Example topics are provided in browseable format
• Access the Consensus FAQ here. 

Semantic Scholar

• SEMANTIC SCHOLAR  PROVIDES BRIEF SUMMARIES  of the main objectives and results of papers. (It supplies underlying data for several of the other tools above).
• "We index over 200 million academic papers from publisher partnerships, data providers, and web crawls."
• "Accelerating Scientific Breakthroughs Using AI"
• Developed by the Allen Institute for AI
• Access Semantic Scholar's FAQ here.

More AI Research Tools!

To learn about additional AI research tools, check out these research guides!

• AI Research Tools (Rutgers University Library)
• AI Research Tools (Georgetown University Library)
• Selected AI Based Literature Review Tools (Texas A&M University)
• Last Updated: Apr 9, 2024 8:34 PM
• URL: https://guides.rider.edu/aitools

What we know about the low-risk anomaly: a literature review

• Open access
• Published: 28 April 2023
• Volume 37 , pages 297–324, ( 2023 )

Cite this article

You have full access to this open access article

• Joshua Traut   ORCID: orcid.org/0000-0003-1627-1297 1  

5257 Accesses

6 Altmetric

Explore all metrics

It is well documented that less risky assets tend to outperform their riskier counterparts across asset classes. This paper provides a structured summary of the current state of literature regarding this so-called low-risk anomaly. It provides an overview of empirical findings across implementation methodologies and asset classes. Furthermore, it presents the most prevailing causes, which are namely exposure to other factors, coskewness risk, investor constraints, behavioral biases, and agency problems. The paper concludes that despite some critiques there are good reasons to believe that the low-risk anomaly can be evaluated as an investment factor. It also identifies that more research is required to disentangle the proposed causes to fully understand the big picture of the anomaly with certainty.

Similar content being viewed by others

Diversification and portfolio theory: a review

Gilles Boevi Koumou

Applications of Explainable Artificial Intelligence in Finance—a systematic review of Finance, Information Systems, and Computer Science literature

Patrick Weber, K. Valerie Carl & Oliver Hinz

ESG Disclosure and Idiosyncratic Risk in Initial Public Offerings

Beat Reber, Agnes Gold & Stefan Gold

Avoid common mistakes on your manuscript.

1 Introduction

Factor investing has gained increasing traction in academia and thousands of papers have been published with regard to this strain of literature (Jensen et al. 2022 ; Harvey 2017 ). Pioneering works developed investment factors that are based on the findings that small (big) firms, firms with low (high) book-to-equity ratios, and firms showing positive (negative) return momentum outperform (underperform) the market (Fama and French 1992 ; Basu 1977 ; Carhart 1997 ; Jegadeesh and Titman 1993 |). In a similar fashion, a persistent outperformance was discovered for low-risk assets in many asset classes [e.g. Frazzini and Pedersen ( 2014 )]. Unlike for the above-mentioned factors, the respective measure to capture low-risk assets is not agreed on, resulting in a variety of proposed low-risk measures. Because the outperformance of low-risk assets directly violates the common assumption that taking risks is rewarded with returns in financial markets, the low-risk investment effect is also called low-risk anomaly. To date, multiple causes for the anomaly have been identified, but there is still no consensus about which rationale prevails. The goal of this paper is to provide a comprehensive overview of the current state of research that examines the empirical identification of the low-risk anomaly across asset classes as well as the causes for its existence.

This is not the first time that the literature covering the low-risk anomaly is reviewed in a stand-alone paper. However, current reviews either focus solely on the causes of the low-risk anomaly (Blitz et al. 2014 ) or are strongly tilted towards equities (Blitz et al. 2020 ). The contribution of this paper is thus threefold. First, it summarizes current findings of the low-risk anomaly across asset classes, markets and methods. Second, it provides an overview of the most employed empirical methods to capture the low-risk anomaly. Thus, rather than just showing the findings of current research, it also gives insights into how those findings were generated. Third, it includes studies that neglect the existence of the low-risk anomaly and therefore provides a balanced overview of the current state of research.

The reading proceeds as follows. Section  2 provides a short historical background on the development of the anomaly. Section  3 collects empirical evidence in various asset classes. Section  4 lists and explains proposed causes for the anomaly. Section  5 discusses the current state of research and provides a general conclusion of the findings.

2 Background

The capital asset pricing model (CAPM) revolutionized the finance literature as it replaced the thought that an asset’s risk is its own volatility with the idea that the relevant measure of risk is how an asset covaries with the market. The CAPM is based on the work of Markowitz ( 1952 ) who defines risk as the variance of returns. He finds that diversification among asset reduces risk and hence increases the risk-return profile of an investment. Idiosyncratic risk can be eliminated and only systematic risk—the market risk of an investment—remains. The effect of diversification is illustrated in Fig.  1 .

Diversification benefits. This figure is based on Markowitz ( 1952 ) and shows that with an increasing number of portfolio holdings the standard deviation of portfolio returns can be reduced. This is due to a reduction of idiosyncratic risk which vanishes as a result of diversification

The idea of the CAPM was first developed by Jack Treynor in a private manuscript (Treynor 1961 ) but was published independently by Sharpe ( 1964 ), Lintner ( 1965 ) and Mossin ( 1966 ). The model is based on Markowitz’s assumption that investors are risk-averse and seek portfolios that provide the highest return at a certain level of risk. An optimal portfolio offers the minimum risk-return ratio at the chosen risk level. As unsystematic risk can be diversified away, systematic risk was thought to be the only variable that mattered to investors. Based on this, the CAPM formula describes the relationship between risk and return for an asset i as

The return of an asset i ( \({\dot{r}}_i\) ) is defined as the risk-free rate ( \(r_f\) ) plus the asset’s market sensitivity ( \(\beta _{i,m}\) ) times the excess return of the market ( \({\dot{r}}_m-r_f\) ). Hence, the only variable controllable by investors to set portfolio returns is their investment’s exposure to the market. The dots indicate absolute returns in Eq. ( 1 ). We can also rewrite Eq. ( 1 ) in a shorter form for the asset’s excess return as

Here, returns without a dot represent excess returns. This notation will be kept throughout the paper. After its publication the CAPM was criticized by a large body of literature because the linear relation between market exposure and returns could not be proven empirically with certainty. Among the early studies, while some confirm that the relation exists (Fama and MacBeth 1973 ), others find that it is much flatter than implied by the CAPM (Black et al. 1972 ; Friend and Blume 1970 ; Miller and Scholes 1972 ) and some even find a negative relationship between risk and return (Haugen and Heins 1975 ). Doubts about the CAPM were further fostered as more later studies could not confirm the linear relationship between market risk and return (Haugen and Baker 1991 , 1996 ; Fama and French 1992 ; Frazzini and Pedersen 2014 ). Similarly, other studies find that risky stocks (in terms of idiosyncratic volatility) underperform their low-risk counterparts (Ang et al. 2006 , 2009 ; Clarke et al. 2010 ). Another body of literature that examines the empirical performance of the theoretical minimum-variance portfolio comes to a related conclusion. These studies find that while the minimum-variance portfolio achieves a significant reduction of volatility, it also delivers comparable or even higher average returns than the market portfolio (Clarke et al. 2006 , 2011 ; Haugen and Baker 1991 ; Jagannathan and Ma 2003 ).

All of the above studies document the so-called “low-risk anomaly”. As different concepts to measure an asset’s risk are applied in the literature, the investment style that captures the anomaly was given various names such as defensive, low-risk, low-volatility, or quality factor. I will call all of these related factors low-risk factors. An overview of the different low-risk factors that were implemented across asset classes is provided in the next section.

3 Evidence in markets

Like most factors, low-risk factors are most researched in equity markets. Regardless, there is a considerable literature that took the concept from equity markets and adapted it to other asset classes. Given this inequality of available literature, the equity section is more extensive than the others.

3.1 Equities

In equity markets three different measures to asses a stock’s riskiness are assessed by literature. These three measures are a stock’s market beta, its idiosyncratic volatility (IV), and it’s total volatility of returns. Relatedly, there also exists a strain of literature that examines the minimum variance portfolio. In this section I will first review the studies that focus mostly on confirming one of the three measures empirically and the mean variance portfolio, before I review studies that compare multiple concepts.

3.1.1 Market beta

As one of the first who detect the low-risk anomaly, in their empirical assessment Black et al. ( 1972 ) not only find that the CAPM does not hold but also propose a new model that captures the flatter linear relationship between systematic risk and return. According to this model an asset’s return is defined as

In addition to the market risk Black et al. ( 1972 ) introduce a second factor return ( \(r_\beta \) ) that captures the flatter relationship between market risk and returns. They call this factor “beta factor” because its coefficient is a function of the asset’s beta. They show empirically that in the US \(r_\beta \) is generally positive. This means that stocks with a low beta earn positive CAPM excess returns whereas high-beta stocks underperform the predictions made by CAPM.

Black ( 1993 ) replicates the study of Black et al. ( 1972 ) and empirically confirms their suggestion that \(r_\beta \) is positive in the US. In doing so, he sorts stocks based on beta and builds ten portfolios—the 10% of stocks with the largest beta in the first portfolio, and so on. He then takes the excess returns from the ten portfolios and weights them by ( \(1-\beta _j\) ), where \(\beta _j\) represents portfolio j ’s beta. The resulting portfolio goes long low-beta stocks and short their high-beta counterparts. Black’s empirical tests show that this beta-neutral portfolio earns positive statistically significant excess returns over the sample period between 1931 and 1991. He concludes that the beta factor indeed earns a positive risk-premium.

Frazzini and Pedersen ( 2014 ) further confirm the existence of a risk factor related to an asset’s beta. They estimate market beta of security i according to the following formula

where \({\hat{\sigma }}_i\) and \({\hat{\sigma }}_m\) are the one-year rolling standard deviations of asset i and the market portfolio m and \({\hat{\rho }}_{im}\) is the five-year rolling correlation between the two. They separate time horizons because correlations appear to move more slowly than volatilities (De Santis and Gerard 1997 ). In 20 developed equity markets they rank stocks on estimated betas every month and form simple portfolios that are long low-beta stocks and short high-beta stocks. Within long and short legs of the portfolios stocks are weighted by ranked betas so stocks with low/high betas have higher weightings in the long/short side of the portfolio. Both legs of the portfolio are then rescaled to have a beta of one, thus making the aggregated portfolio beta neutral. Over the sample period 19 out of the 20 betting against beta (BAB) country portfolios earn positive excess returns of which eleven are statistically significant at the 5% level. Han et al. ( 2020 ) apply the same factor construction methodology to Chinese A-shares (a region not covered by Frazzini and Pedersens’s study) and show that the BAB factor also earns a statistically significant alpha in this region.

Asness et al. ( 2014 ) also follow the methodology of Frazzini and Pedersen to investigate BAB portfolios in the US, Japan, Europe ex-UK, and UK. They deviate from the previous methodology in that they use BARRA risk models Footnote 1 to estimate volatilities and correlations in Eq. ( 3 ). To form country portfolios they calculate z-scores based on a stocks beta rank. They use these z-scores as standard weights for the long-short portfolio construction as z-scores add up to zero. Then they volatility-adjust the long and short side of the portfolio to have equal volatilities and scale the final portfolio to have a volatility of 10%. Each month they create such low-risk long-short portfolios in each region and aggregate them to a global low-risk portfolio with the following weights: US, 50%; Japan, 16.7%; Europe ex-UK, 16.7%; and UK, 16.7%. Their resulting portfolio earns positive excess returns that have an average Sharpe ratio of 0.61 in the sample period from 1990 to 2013.

3.1.2 Idiosyncratic volatility

Ang et al. ( 2006 ) take a different angle at quantifying the low-risk anomaly. Given the empirical failure of the CAPM and the ubiquity of the three-factor model by Fama and French ( 1992 ) (FF3) they quantify a firms riskiness as its residual volatility relative to the FF3 model. More precisely, they define a stock’s idiosyncratic risk as \(\sqrt{var(\epsilon _i)}\) resulting from the following equation

where SMB , and HML are referring to the size and value factor of the FF3 model. Ang et al. ( 2006 ) compute monthly IVs for U.S. stocks with the above regression formulas using daily return data. They sort stocks into quintile portfolios based on their IV, for which they calculate value-weighted returns and rebalance them every month. Over their sample period from 1963 to 2000 they report statistically significant negative CAPM and FF3 alphas for a portfolio that goes long high-risk stocks and shorts their low-risk counterparts. Ang et al. ( 2009 ) reinforce the findings in a subsequent study within which they apply the same methodology to a larger sample of 23 developed countries. Again they find that high-risk stocks tend to earn significantly lower returns than low-risk stocks. A more recent study by Dimson et al. ( 2017 ) further confirms the out-of-sample validity of the results. They estimate a stock’s idiosyncratic risk as the three-month volatility of \(\epsilon _i\) in Eq. ( 4 ). In their two samples covering US and UK stock markets low-risk stocks earned average annual returns of 10.9% and 11.6% each year while high-risk stocks earned 4.1% and 4.2% respectively.

3.1.3 Total return volatility

Arguably the simplest measure to quantify riskiness of stocks is employed by Blitz and van Vliet ( 2007 ) for large cap stocks in the FTSE World Developed index between 1985 and 2006. They construct monthly equally-weighted decile portfolios within which they rank stocks on their past three-year volatility of weekly returns. Across those volatility-sorted portfolios excess returns rise accompanied with a fall in volatilities, leading to a monotonic decrease in Sharpe ratios from 0.72 to 0.05 starting at the low-volatility portfolio.

Following Blitz and van Vielt’s research on developed markets, Blitz et al. ( 2013 ) reinforce the findings by expanding the methodology to emerging markets. They sort stocks covered in the S &P/IFC Investable Emerging Markets Index based on historical three-year volatility of weekly returns. Their quintile country-neutral portfolios that have the lowest volatility significantly outperform the counterparts exhibiting the highest volatility. Joshipura and Joshipura ( 2016 , 2019 ) use the same sorting methodology for the Indian stock markets and confirm the finding that low-volatility stocks generate outperformance

Baker and Haugen ( 2012 ) extend the study to 21 developed countries and 12 emerging markets. Every month they build decile portfolios based on a stock’s return volatility over the past 24 months using monthly return data. In their sample period from 1990 to 2011 they find that in every market the lowest risk decile portfolio earns higher returns than the portfolio holding the riskiest stocks.

3.1.4 Minimum variance portfolio

The minimum variance methodology differs from the above examined methods in that it does not attempt to separate risky stocks from its less risky counterparts. Instead, it attempts to form a portfolio that has minimum total variance. In doing so, risky stocks may be added to the portfolio if they reduce total risk, for example if they are negatively covary with other stocks.

Haugen and Baker ( 1991 ) investigate the performance of the minimum variance portfolio versus the market portfolio between 1972 and 1989. They use the largest 1000 US stocks to quarterly form the minimum variance portfolio based on the historic covariance matrix over the last 24 months. They also impose constraints to ensure diversification and abandon short-selling. In their sample period, the minimum variance portfolio has a lower volatility and earns higher returns than the Wilshire 5000 index that proxies the market portfolio. Further evidence that the minimum variance portfolio generates outperformance—even when reallocated less regularly is gathered by Jagannathan and Ma ( 2003 ). Similar to Haugen and Baker ( 1991 ) they build the minimum variance portfolio imposing diversification and short-selling constraints for 500 randomly chosen stocks traded on NYSE and AMEX. They reallocate the portfolio on a yearly basis and show that it earns much higher returns at lower variation than the market portfolio. Clarke et al. ( 2006 ) extend the study of Haugen and Baker ( 1991 ) to cover the time horizon from 1968 to 2005 and to use additional covariance structuring methodologies. More precisely, they use principal components following Connor and Korajczyk ( 1988 ) and Bayesian shrinkage following Ledoit and Wolf ( 2004 ). Based on monthly (daily) returns of the largest 1000 stocks in the US they estimate two structured covariance matrices for the past 60 months (250 days) and compose the minimum variance portfolio imposing short-selling and diversification constraints. For both structuring methodologies they find that minimum variance portfolios have about 75% of the realized risk of the general market, but earn similar returns. They replicate their results using the same methodology in Clarke et al. ( 2011 ) from 1968 to 2009 and find that the minimum variance portfolio outperforms the market regarding both, risk and return. Chen et al. ( 2018 ) investigate minimum variance portfolios calculated from daily returns over the past two years in the Chinese A-shares market and find that these portfolios strongly outperform the market regarding risk and return.

3.1.5 Comparison of measures

With multiple measures employed to capture the low-risk factor, the question which one does it best automatically arises. This question was investigated by multiple studies though only few investigate all four above presented methods.

Blitz and van Vliet ( 2007 ) compare the performance of their proposed measure of total return volatility to market beta. Same as for return volatility, they rank stocks based on three-year historical regional betas. Though they find the same pattern in portfolio returns—that lower risk portfolios outperform—this pattern is more irregular and less strong for portfolios sorted beta than it is for those sorted on total return volatility. Baker et al. ( 2011 ) perform the same comparison and sort stocks on five-year volatility and beta into quintile portfolios. They find that low risk portfolios consistently outperform from 1968 to 2008 in the US and also report that the effect of volatility is larger than that of beta.

Soe ( 2012 ) also compares two of the proposed methodologies—low-volatility and minimum-volatility strategies. They find that the two approaches exhibit very similar performance characteristics. De Carvalho et al. ( 2012 ) confirm the similarity of low-risk factor strategies. They investigate five popular low risk portfolios and find that they generally load on low-beta and low-volatility factors. Furthermore, they find that the performance of these portfolios is relatively similar. Scherer ( 2011 ) and Chow et al. ( 2014 ) come to the same conclusions in their studies on widely used low-risk strategies.

Walkshäusl ( 2014 ) compares the low-volatility, the low-beta, and the minimum volatility strategy for the MSCI universe of developed and emerging markets between 2001 and 2011. Regarding low-volatility and low-beta he follows Baker et al. ( 2011 ) and builds portfolios based on the historic five-year measure of the respective style. The minimum volatility portfolio is proxied by MSCI minimum volatility indices. Walkshäusl compares the performance of the quintile portfolios with the minimum betas/volatilities with the minimum variance portfolio. Parts of his analysis are visualized in Fig.  2 . He finds that though strategies generate higher returns than the market benchmark, these differences are not statistically significant. Also, between strategies return differences are relatively small. Standard deviations of the three strategies are substantially lower than that of the market and statistically significant for all style portfolios. Again, differences between strategies tend to be small.

Comparable to the pattern in equity markets, in bond markets literature finds that low-risk bonds tend to outperform. Most literature defines specific factors for government bonds and corporate bonds separately. Because of this, the two asset classes will be examined separately in this section. In general, the most promising risk-adjusted returns in both asset classes can be earned with bonds that are characterized by short maturities and high credit ratings (Ilmanen et al. 2004 ).

3.2.1 Government bonds

Pilotte and Sterbenz ( 2006 ) study Treynor and Sharpe ratios for US Treasury securities between 1959 and 1997. They find that both ratios are highest for short-term bills and decrease as maturity rises. Same as for equities, Frazzini and Pedersen ( 2014 ) use beta to determine the riskiness of a bond. They define beta as the sensitivity of the bond to an equally-weighted portfolio of all Treasuries used in the analysis and build seven beta ranked portfolios. They find that between 1952 and 2012 low-beta Treasuries earn positive alphas that turn negative for their high-beta counterparts. Also, Sharpe ratios increase from low-beta to high-beta portfolios and a long-short of the lowest and highest portfolio delivers the highest significant Sharpe ratio of 0.81. It has to be noted that though they rank Treasuries based on beta, this is empirically equivalent to ranking on duration or maturity. Hence, they confirm the results of Pilotte and Sterbenz ( 2006 ). Brooks et al. ( 2018 ) take a similar route and employ effective duration as the measure for government bond risk. They sort bonds into three portfolio buckets based on duration across 13 developed markets. A long-short portfolio that buys (sells) the most (least) favorable bucket earns an average return of 1.04% p.a. The same methodology is used by Kothe et al. ( 2021 ) in a later analysis who report significant excess returns of 0.77% p.a. for this strategy. Focusing on 20 non-US developed bond markets Durham ( 2016 ) confirms the return generation of low-risk government bond strategies. He uses the methodology of Frazzini and Pedersen ( 2014 ) but performs minor tweaks such as taking daily instead of monthly data for the portfolio construction. Over his sample period from 1962 to 2013 he reports an average excess return of 25 bps per month for the BAB long-short portfolio.

Monthly CAPM and FF3 alphas of low-risk investment strategies in different markets. This illustration is based on the results reported in Walkshäusl ( 2014 ). It shows CAPM and FF3 alphas for low-volatility, low-beta, and minimum volatility strategies in developed markets (DM), the European Union (EU), Japan (JP), the US, and emerging markets (EM). Strategies are based on the MSCI universe between 2001 and 2011. Low-volatility and low-beta returns are represented by the quintile of stocks that have the lowest respective measure each month. The minimum volatility strategy is proxied by MSCI minimum volatility indices

Few studies extend analyzed assets beyond developed markets. Zaremba and Czapkiewicz ( 2017 ) perform a broad market study across 25 developed and emerging markets. They take modified duration as the relevant low-risk measure to build long-short portfolios after sorting bonds into tercile buckets. They report that this strategy earns average significant returns of 0.27% p.a. across all markets.

3.2.2 Corporate Bonds

The methodologies used for corporate bonds are similar to those for government bonds. Derwall et al. ( 2009 ) find that low-maturity corporate bonds outperform their long-maturity counterparts in the US. Aussenegg et al. ( 2015 ) report the same finding in European corporate bond markets. Using the same methodology as for their government bond analysis, Frazzini and Pedersen ( 2014 ) build long-short portfolios for US corporate bonds based on their sensitivity to an equally-weighted portfolio of all corporate bonds used in the analysis. They report that alphas and Sharpe ratios of corporate bond portfolios increase for portfolios that hold more low-risk assets.

To enhance the robustness of low-risk corporate bond strategies, a strain of literature developed that extends these strategies with fundamental measures of risk. This more comprehensive approach is used by Brooks et al. ( 2018 ) who focus on public companies in 13 developed markets and Israel et al. ( 2018 ) who solely cover the US market. Similar to the strategies above, low duration is one criterion characterizing a low-risk security. Additionally, market leverage computed as

and gross profitability computed as

are taken as measures to identify low-risk corporate bonds. Within both studies, assets are broken down into quintiles according to the aggregated low-risk factor. From the least to the most favorable quintile, returns rise while volatility either decreases or remains at the same level. The best risk-return ratio is achieved when a long-short portfolio of the first and the last quintile is built.

A more simplified approach that incorporates fundamental measures is employed by Houweling and van Zundert ( 2017 ) who use maturity and rating to define a low-risk portfolio for the US corporate bond market. They construct two asset pools, one for investment-grade and one for high-yield bonds, arguing that the assets in those pools differ substantially in terms of market participants and other market characteristics. Within both pools, they favor short-dated, high-rated bonds and create a long-short portfolio that buys the top 10% of the most favorable bonds and sells the bottom 10% of investible assets. In both markets, significant excess returns can be earned with this strategy.

De Carvalho et al. ( 2014 ) test five risk metrics in developed investment-grade corporate bond markets that are denominated in USD, EUR, GBP, and JPY between 1997 and 2012. The risk metrics are duration-times-yield (or yield elasticity), modified duration, yield to maturity, duration-times-spread, and option-adjusted spread. Based on these measures they form quintile portfolios and find that duration-times-yield sorted portfolios show the biggest differences in Sharpe ratios between the lowest and the highest portfolio irrespective of the underlying currency. Also, alphas for low-risk portfolios are positive and turn negative for the corresponding high-risk portfolios for four out of the five risk measures used in the analysis.

Lastly, Chung et al. ( 2019 ) run a comprehensive analysis of low-risk investing in corporate bond markets and find that bonds that have more exposure to aggregate market volatility earn lower returns—even when adjusted for bond characteristics such as ratings and maturities. In contrast to the equity literature, they also find that bonds with a higher IV over the past six months calculated similarly to Eq. ( 4 ) but with different factors have higher returns. However, they also document that bonds with high stock return volatility have lower expected returns.

The low-risk anomaly is apparent in almost every market. This section only presents a small extract of the existing literature, primarily to show how widespread the outperformance of low-risk assets is in different markets.

In addition to stocks and bonds Frazzini and Pedersen ( 2014 ) apply their BAB factor to credit indices, equity indices, commodities and foreign exchange. Following the same methodology as discussed in Sect.  3.1 , they form portfolios sorted on beta and document that their long-short BAB portfolios generate positive excess returns. Frazzini and Pedersen ( 2022 ) further investigate the low-risk anomaly in options and levered ETFs. They find that the higher the leverage, the lower the risk-adjusted return of such products. They further demonstrate that BAB factor portfolios earn large and statistically significant abnormal returns with Sharpe ratios above one. Similarly, Cao and Han ( 2013 ) find that returns of delta-hedged options decrease with an increase in the IV of the underlying stock.

The low-risk anomaly does not solely hold for investments of all kind but also for investment professionals. Jordan and Riley ( 2015 ) document that the low-risk anomaly is also present in the cross section of mutual fund returns, meaning that funds with low return volatility tend to outperform their peers.

In more fragmented financial markets, the pattern can also be observed. Eraker and Ready ( 2015 ) find that very risky over-the-counter stocks have very poor average returns. Similarly, Moskowitz and Vissing-Jørgensen ( 2002 ) find that despite being more risky, private equity stocks do not deliver higher returns than publicly traded stocks, making them unattractive from a risk-return standpoint. Relatedly, Adhami et al. ( 2023 ) observe an inverse relationship between risk and return in crowdlending markets.

Lastly, a very comprehensive study by Falkenstein ( 2010 ) detects the low-risk effect in 20 asset classes. This study does not solely focus on common financial assets such as equities and bonds but also incorporates more exotic fields such as movie production, lotteries, and sports bets.

3.4 Replicability and robustness

In the presence of multiple factors that claim to capture the low-risk anomaly, a discussion developed whether it makes sense to claim significance for factors that are almost identical. Harvey ( 2017 ) addresses this issue and states that too much attention is drawn on p-values. He claims that since significant results are more likely to be published, there is a strong incentive for p-hacking and data manipulation in factor research. Harvey et al. ( 2016 ) share this view and argue that t-stat boundaries to assess significance should be much higher for factors. They show that there is a publication bias, meaning that new factors are more likely to be published than replication studies of existing ones. Furthermore, they demonstrate that the performance of published factors tends to degrade after publication, which as they argue is an indicator for data-mining and p-hacking in the factor literature. In a very comprehensive study Jensen et al. ( 2022 ) address this critique. They replicate 153 factors that they cluster into 13 themes in 93 countries and assess their replicability. The theme “Low risk” is found to have a replication rate of 100% in the US, developed ex. US, and emerging equity markets. Other studies deliver contrasting results. One study replicates 452 anomalies across different time horizons and shows that for low-risk equity factors low-risk stocks outperform their high-risk peers but in most settings they don’t pass the 5% significance hurdle (Hou et al. 2020 ). Pyun ( 2021 ) similarly finds that the IV premium significantly decreased after the seminal paper by Ang et al. ( 2006 ) was published. Though all of these studies find a premium, the contrary results for its significance indicate that a critical view of the anomaly may be worthwhile.

Regarding robustness, many of the studies that examine the low-risk anomaly perform robustness tests with respect to other common risk factors and macroeconomic variables. For example Frazzini and Pedersen ( 2014 ) calculate alphas of their BAB factor to FF3 factors and momentum and find that BAB alphas remain significant. Another example is the study composed by Ang et al. ( 2009 ) who control for the FF3 factors, momentum, volume, and liquidity. They also find, that their excess returns cannot be explained by the control variables.

Based on the findings of Baker et al. ( 2011 ) who report that the low-risk effect is stronger for smaller stocks than for larger stocks, low-risk factors have been criticized as many anomalies are known to be concentrated in small-cap stocks and therefore difficult to exploit. For example, Novy-Marx and Velikov ( 2022 ) criticize the methodology behind the BAB factor because high parts of its premium are driven short selling highly illiquid micro caps. Other scholars do not support those claims and show that for example, the IV factor is especially robust when penny stocks are excluded (Chen et al. 2020 ). Relatedly, Auer and Schuhmacher ( 2015 ) show that the low-risk anomaly is strongly present among the largest, most liquid US stocks.

Other studies deliver more support for low-risk factors and show that their excess returns do not stem from industry or country bets (Asness et al. 2014 ; Baker et al. 2014 ). Exposure to interest rate risk as a possible explanation was examined by De Franco et al. ( 2017 ) who conclude that, although low-risk stocks are significant exposed to interest rate risk, this only explains a very small part of their outperformance.

However, there are also more critical voices in literature. Cederburg and O’Doherty ( 2016 ) investigate the performance of beta sorted portfolios. They find that properly accounting for time-series variation of portfolio risk properly explains the low-risk anomaly. In other words, taking into account that beta is not constant over time, vanishes the anomaly. In their analysis they use a conditional CAPM, following Boguth et al. ( 2011 ), within which beta is modeled as a function of lagged state variables, a procedure also known as standard instrumental variable method. Another more critical study attributes the IV effect to liquidity. It shows that when taking quote-midpoint returns the IV effect vanishes and attributes the anomaly to bounces in trade prices (Han et al. 2015 ).

4 Proposed causes

Even though a lot of empirical evidence exists that supports the existence of a low-risk anomaly, no consensus about the rationales behind it is reached. There are rational and irrational theories why low-risk factors generate excess returns. First, I will cover the rational explanations such as coskewness risk, exposure to other factors, and investor constraints before I will elaborate on studies delivering behavioral explanations. Though I attempt so clearly separate between proposed causes, note that there are strong interrelations and the categorization here is only done to provide some structure.

4.1 Exposure to other factors

In the presence of multiple factors that attempt to measure the low-risk anomaly, there are a number of studies that investigate the interrelations of different low-risk factors. In his comparison of low risk strategies Walkshäusl ( 2014 ) regresses the returns of minimum variance, low-beta, and minimum total return volatility strategies in different regions on the returns of the same strategy in developed markets. He finds that all strategies in developed markets share a significant common return component that is not shared with emerging markets. Asness et al. ( 2019 ) dig deeper into this discovery and directly disentangle the two driving components of the BAB strategy, volatility and correlation. They find that both, volatility and correlation contribute equally to the performance of the BAB factor. In a similar fashion Chen and Petkova ( 2012 ) decompose the IV factor into exposure to market variance and exposure to market correlation. They find that only variance is priced and has a negative premium. Further they show that the differences in performance between high (low) IV factor portfolios have positive (negative) loadings with respect to innovations in average stock variance. Because of the negative premium such portfolios earn lower (higher) expected returns. In his study Scherer ( 2011 ) investigates the performance of minimum-variance portfolios. He finds that when controlling for low-beta, residual return volatility as well as the market return factors, 79% of the variance in returns of minimum variance portfolios can be explained. He infers that outperformance by minimum variance portfolios is subsumed by other low-risk factors.

Beyond low-risk factors there are also other studies suggesting that low-risk factors have exposure to other factors and thus generate outperformance. In his influential paper Fu ( 2009 ) finds that high returns of high volatility stocks are largely explainable by the short-term return reversal of small cap, high-volatility stocks. In other words, stocks with high risk have high contemporaneous returns that tend to reverse in the following month. This claim is supported by the finding of Huang et al. ( 2010 ) who report that return reversals can explain the low-risk anomaly. However, other studies document that the results in Fu ( 2009 ) are prone to look-ahead bias and thus not useful to overturn the findings of low-risk premia (Park et al. 2020 ; Fink et al. 2012 ; Guo et al. 2014 ). Size is another common factor that is claimed to render the low-risk anomaly insignificant. Riskier stocks tend to be small while low-risk stocks are most likely large caps. Creating buckets with equal market capitalization share in the portfolio sorts based on IV causes all buckets to generate the same returns, thus eliminating the low-risk effect (Bali and Cakici 2008 ). These findings are further confirmed for other low-risk strategies by Hou et al. ( 2020 ) and Pyun ( 2021 ). Novy-Marx ( 2016 ) challenges low-risk strategies in an integrated approach by controlling for size, profitability and value. In line with the studies mentioned in Sect.  3.4 , when controlling for the FF3 factors, he confirms that low-risk strategies generate alpha. However, he shows that this outperformance is generated because low-risk strategies short unprofitable small growth firms. Hence, the low-risk anomaly can be explained by combining value, size and profitability factors. Fama and French ( 2016 ) further support the finding and argue that low-beta returns can be explained by their profitability and investment factors. These finding is also bolstered by the theory of Johnson ( 2004 ) who shows that leverage ratios of firms (usually a measure for profitability) can explain the low-risk anomaly. Generally, when comparing common profitability factors [e.g. Asness et al. ( 2018 )] to low-risk factors some commonalities can be identified—especially in corporate bond markets. For example, gross profitability and leverage, both profitability factors, are used as variables to identify low-risk corporate bonds. The inclusion of such fundamental values also led to a discussion whether profitability factors are related to value factors (Novy-Marx 2013 ).

4.2 Skewness risk

Another popular explanation for the low-risk anomaly is that it compensates investors for skewness risk. There are two sides of this theory that are going to be covered separately here. While this section focuses on the rational explanations of the skewness risk premium, the behavioral side of the premium is covered later in Sect.  4.4 under “Preference for Lotteries”.

The reasoning to attribute the low-risk anomaly to skewness is pretty straight forward. Most asset pricing models do not reach beyond the second moment of returns (e.g. covariance in the CAPM) and hence skewness is not included in most pricing kernels. The fact that skewness of returns can change the expected value of asset returns is thus ignored and traditional pricing models diverge from empirically observed prices. The studies of Rubinstein ( 1973 ) and Kraus and Litzenberger ( 1976 ) suggest that the empirical failure of the CAPM may be attributable to ignoring the effect of skewness in asset returns. More precisely, their findings indicate that investors demand compensation for accepting negatively skewed returns. Harvey and Siddique ( 2000 ) build upon this idea and develop an asset pricing model that incorporates skewness. They extend the CAPM by an additional term which makes their pricing function

where the additional term \(\beta _{i,s}\) represents the sensitivity of stock i to the squared market return ( \(r_{m}^2\) ) and thus measures the stock’s coskewness with the market. Harvey and Siddique ( 2000 ) test their model empirically and find that the model indeed helps to explain the cross-section of equity returns. Schneider et al. ( 2020 ) take this enhanced asset pricing model and directly relate it to low-risk anomalies. First, they show that the residual returns of long-short portfolios based on beta and IV are associated with negative skewness. To further allocate the performance of low-risk strategies to negative skewness, they build factors based on ex-ante skewness. In doing so, they extract implied skewness from option prices following Schneider and Trojani ( 2015 ) and build four factors of implied skewness that earn positive excess returns with which they control for skew exposure in low-risk strategies. Their results show that controlling for each of their four factors significantly reduces negative coskewness of residual returns and largely eliminates alphas of low-risk strategies built on beta and IV. The reductions of alpha are so pronounced that the remaining alpha of the low-risk strategies becomes statistically insignificant.

Boyer et al. ( 2010 ) also investigate the relation of implied skewness and low-risk strategies. They follow Chen et al. ( 2001 ) using firm-level variables to predict idiosyncratic skewness of stocks. The results of their analysis indicate that idiosyncratic volatility is a strong predictor of idiosyncratic skewness. When they control for their skew measure in IV factors they find that excess returns become much lower and statistically insignificant. Relatedly, Bali et al. ( 2020 ) argue that idiosyncratic skewness of returns can be used to measure firms’ growth options. With their skewness-based measure they reason that investors prefer stocks with a large number of embedded growth opportunities. They show that when controlling for their measure of firms’ growth options the IV anomaly can be strongly reduced. Their line of reasoning is supported by other studies that also find that the low-risk anomaly vanishes when controlling for growth options (Bhamra and Shim 2017 ; Barinov and Chabakauri 2021 ).

4.3 Investor constraints

Literature has found multiple investor constraints that are thought to cause the low-risk anomaly. I split those causes into borrowing/leverage constraints and short-selling constraints.

4.3.1 Borrowing/leverage constraints

The reasoning behind this theory is pretty straight forward. If agents are constraint regarding their leverage, the points on the capital market line that lie above the tangency portfolio are out of reach for those agents. The only way they can earn higher returns is to buy riskier assets that are located further up on the efficient frontier. These constrained agents bid up prices of riskier assets and cause the low-risk anomaly. This theory is illustrated in Fig.  3 where the dotted line represents the theoretical security market line and the dashed line shows the expected security market line with no leverage available for agents. The red semicircles indicate some agent’s utility function.

Security Market Line with no Leverage. This figure illustrates the arguments made by Frazzini and Pedersen ( 2014 ). It shows the efficient frontier of an investment universe (grey line) and the respective capital market lines for investors wo can or cannot use leverage (blue lines). The figure shows that an unconstrained investor can reach investments on the capital market line above the tangency portfolio by using leverage (dotted blue line). The investor who cannot use leverage falls back on the efficient frontier above the tangency portfolio (dashed blue line). Above the tangency portfolio his capital market line is less steep than that of the unconstrained investor. The dashed blue line thus represents the capital market line for investors who cannot use leverage. The red utility curves demonstrate that the unconstrained investor (dashed red line) can invest into more favorable portfolios above the tangency portfolio than the investor facing leverage constraints (solid red line). (Colour figure online)

Contemporaneous to the first empirical findings that detected the low risk anomaly Black ( 1972 ) and Brennan ( 1971 ) showed in their theoretical works that a restriction on investor borrowing reduces the slope of the capital market line. This extension of the CAPM brings it closer to the empirical findings of that time. When Black ( 1993 ) revisited the low-risk anomaly, he also claimed that borrowing restrictions enforced by law (like margin rules, bankruptcy laws, and tax rules) are the reason why the anomaly exists.

Frazzini and Pedersen ( 2014 ) lay out convincing arguments for leverage constraints being the cause for the low-risk anomaly. They predict that if a funding liquidity shock occurs, required returns on their BAB factor rise, leading to losses in the current BAB portfolio. This is expected because agents may need to de-lever their current BAB portfolios or stretch further to buy high-beta assets. Furthermore, they reason that when a liquidity shock occurs, all prices drop simultaneously and betas converge towards one. They are able to bolster their theory empirically as they show that their BAB factor performs worse when funding constraints are higher and also confirm that betas converge when funding conditions are less uncertain. In doing so, they take the TED spread and its volatility as a proxy for funding conditions and funding uncertainty. In addition to the, empirical support of their theory, they further show that investors who are constrained in leverage, such as mutual funds (because they have to hold cash to meet redemptions) hold portfolios with betas above one on while unconstrained firms like leveraged buyout funds hold assets with betas below one. Jylhä ( 2018 ) adds on to the findings of Frazzini and Pedersen ( 2014 ) and further confirms their theory empirically. He measures investor’s leverage constraints using the minimum level of margin required when purchasing stock on credit that is set by the Federal Reserve. Consistent with the theory he finds that when margin requirements increase, the security market line significantly flattens, making the BAB factor more profitable. Boguth and Simutin ( 2018 ) take a different route to the problem. They invert the argument and take the average market beta of mutual funds (who are assumed to face leverage restrictions) as a proxy for investor’s leverage constraints. They show that this proxy predicts returns of the BAB portfolio, strengthening the argument for a connection between leverage constraints and abnormal low-risk returns.

Adrian et al. ( 2014 ) also approach the explanation from another angle as they construct an intermediary stochastic discount factor based on theory covering shocks to leverage of security brokers. They find that this leverage factor correlates strongly with BAB portfolios and explains the cross-section of returns sorted on betas. In their decomposition of the BAB factor Asness et al. ( 2019 ) also test the leverage constraint theory. They show that the BAB factor can be predicted by margin debt held by customers at NYSE member organizations relative to the market capitalization of those NYSE firms, a measure for severity of leverage constraints. In their study focusing on leveraged options and ETFs Frazzini and Pedersen ( 2022 ) show that BAB factors also work in those products. The findings are related to the theory that leverage constraints cause the anomaly because the they show that investors are willing to pay a premium for securities with embedded leverage, and intermediaries who meet this demand need to be compensated for their costs and risk. Lastly, Asness et al. ( 2012 ) lay out the theory in a portfolio allocation problem between bonds and stocks. They also reason that leverage constraints lead investors to allocate portfolio suboptimally from a theoretical perspective.

4.3.2 Short-selling constraints

The theory behind the reasoning why short-selling constraints cause the low-risk anomaly is closely related to behavioral reasons that are covered hereafter. In contrast to the leverage constraint theory, it does not explain the low-risk anomaly as a whole but rather gives insights into why risky stocks are overpriced.

Generally, this literature assumes that there is divergence of opinion about the fair price of an asset. The scarcity of short-selling can thus cause a price to rise above the aggregate valuation of investors. Pessimistic investors are unable to express their view on the development of the asset in trades and thus prices are generally set by optimists. This effect of short-selling constraints on prices is highest when difference of opinion is high. Hence, there must be a negative correlation between risk-adjusted returns and dispersion of beliefs. This theoretical outline and the effect of short-selling constraints is pioneered by Miller ( 1977 ). Similar asset pricing predictions are outlined in other theoretical papers such as those by Duffie et al. ( 2002 ), Morris ( 1996 ), Chen et al. ( 2002 ) and Hong and Sraer ( 2016 ).

The claims made by the theories above have been challenged and confirmed by empirical studies. Dieter et al. ( 2002 ) use the standard deviation in analysts’ forecasts about future earnings to proxy for divergence of opinion among investors. They show that stocks with a wide range of opinions will earn lower returns than otherwise similar stocks. These results are confirmed by other studies who follow their methodology to identify controversial stocks (Hong and Sraer 2016 ; Gebhardt et al. 2001 ).

Figlewski ( 1981 ) takes a different route and sorts constituents of the S &P 500 index into decile portfolios based on short sale interest relative to the total amount of outstanding shares for each stock. According to his reasoning, high short interest indicates high divergence of opinion. He finds that with increasing short interest, the performance of the decile portfolios gets worse. Thus, he confirms that stocks with more controversial information are overpriced and consequently earn lower returns. Chen et al. ( 2002 ) criticize the assumption that short interest can be used to proxy divergence of opinion and instead take breath of ownership as a proxy. They define breath of ownership as the number of investors who have long positions in a particular stock. Low breath means high divergence of opinion because many investors do not express their pessimistic view due to short-selling constraints. Using mutual fund data they find support for their hypothesis and show that stocks with the lowest breath in ownership underperform their peers.

Danielsen and Sorescu ( 2001 ) tackle the problem from a different angle. They argue that with the introduction of options, short-selling constraints on the underlying stock are mitigated. In their empirical analysis they show that option introductions are accompanied with a contemporaneous increase in short interest of that stock and a price decline. This finding also supports the hypothesis that short-selling constraints cause overpricing of assets.

A more narrow study is provided by Stambaugh et al. ( 2015 ) who investigate the IV factor and allocate the low-risk anomaly to arbitrage risk. According to them stocks with high IV have the highest arbitrage risk. At the same IV level, this effect should be seen more dramatically in overpriced stocks as due to short-selling constraints more investors could arbitrage away mispricing in underpriced stocks. Stambaugh et al. ( 2015 ) investigate their claims and measure a stock’s mispricing via 11 return anomalies that survive adjustment to the FF3 model. Given this proxy for arbitrage, they show that as predicted, the low-risk anomaly is significantly negative (positive) among the most overpriced (underpriced) stocks, and the negative effect among the overpriced stocks is significantly stronger. Further they show that the negative effect among overpriced stocks is stronger for stocks less easily shorted, as proxied by low institutional ownership. Liu et al. ( 2018 ) expand the approach of Stambaugh et al. ( 2015 ) and attempt to explain the low-risk anomaly based on beta. They show that the anomaly is only present in the most overpriced segment of stocks. Further they show that when controlling for IV, the anomaly vanishes.

4.4 Investor behavior

In the area of finance there is a large strain of literature focusing on investors’ behavior. Numerous behavioral biases can be related to irrational pricing and thus be argued to cause the low-risk anomaly. Within this section, I will present two of the most commonly referred two biases, which are overconfidence and preference for lotteries of investors. Regardless, these two behavioral biases are certainly not an exhaustive list for behavioral explanations of the low-risk anomaly.

4.4.1 Overconfidence

Overconfidence is a common phenomenon that is not only omnipresent in finance [e.g. Fischhoff et al. ( 1977 ), Kahneman and Tversky ( 1973 )]. Generally, overconfidence refers to the fact that most individuals think they can perform a certain task better than average. In finance this imposes that investors put too much emphasis on their predictions. Furthermore, they are likely to be active in more volatile stocks because in this segment the highest returns can be earned and an active investor can demonstrate his skill the most. Both of the above lead to an overpricing of risky stocks (Blitz et al. 2014 ). Overconfidence is also closely related to short-selling constraints. Similarly, the phenomenon is most common when the extent of disagreement among investors is high. As argued before, this is especially the case for high-volatility assets (Cornell 2009 ; Baker et al. 2011 ). The claims are bolstered empirically in various studies. The findings are that, on average, self-directed individual investors do trade suboptimally, lowering their expected returns through excessive trading (Odean 1999 ; Barber and Odean 2000 , 2001 , 2002 ).

A related area of study focuses on attention-grabbing stocks. This literature argues that investors are likely to buy stocks that grab their attention. In a sense, they overestimate their knowledge about such stocks, which is why this literature can be related to overconfidence. The study of Barber and Odean ( 2008 ) focuses on attention-grabbing stocks and argues that high-risk stocks are more likely to grab attention (e.g. because of extreme price movements or news coverage). This causes a strong upward pressure on prices of such stocks, which flattens the risk return relationship postulated by the CAPM. The claim that investors are likely to buy stocks that are more attention grabbing is supported by the findings of Grullon et al. ( 2004 ). They document that firms with high advertising spending have a larger number of individual and institutional investors.

Viewing overconfidence of investors more broadly, it can also be interpreted as investor sentiment. Baker and Wurgler ( 2006 ) measure investor sentiment via aggregating six proxies (e.g. share turnover) that they orthogonalize to several macroeconomic conditions. They find that after times of low sentiment, small and risky stocks tend to earn excessive returns. This indicates that as sentiment improves, investors bid up prices of risky stocks, which is in line with the theories outlined above. Further, Stambaugh et al. ( 2015 ) use the methodology of Baker and Wurgler ( 2006 ) to investigate the IV factor. They show that the negative (positive) returns of overpriced high-volatility (underpriced low-volatility) stocks is significantly stronger when investor sentiment is high (low). In other words, strong investor sentiment increases the magnitude of the low-risk anomaly.

4.4.2 Preference for lotteries

While it is already shown in Sect.  4.2 that coskewness risk is an explanatory variable for the low-risk anomaly, there is also a strain of literature, that focuses more on the behavioral aspect of investors’ preference for coskewness.

Kumar ( 2009 ) documents that some individual investors prefer stocks with lottery-like payoffs. Such stocks are characterized by a low price with high volatility and skewness. In other words, they offer a small chance for high returns in the short term at low costs. Barberis and Huang ( 2008 ) model this preference with the cumulative prospect theory of Tversky and Kahneman ( 1992 ). Cumulative prospect theory is a modified version of the prospect theory by Kahneman and Tversky ( 1979 ) within which individuals evaluate risks using a utility function that is defined over gains and losses. Barberis and Huang ( 2008 ) demonstrate that with their model a lottery-like security with positively skewed returns can be overpriced by investors, thus earning negative average excess returns. They attribute this to investors preference for lotteries and argue that rational investors cannot arbitrage away this irrationality. Brunnermeier et al. ( 2007 ) also provide a theoretical model that captures investors’ preference for lottery-like stocks. Building on the model of Brunnermeier and Parker ( 2005 ) within which investors care about expected future utility flows and are happier if they overestimate the probabilities of states of the world in which their investments pay off well. Hence, this theory is also very closely related to the above-discussed issue of overconfidence. With their model Brunnermeier et al. ( 2007 ) show that in equilibrium investors make suboptimal decisions and favor lottery-like stocks.

Kumar et al. ( 2011 ) confirm the existence of lottery-preferences by controlling for investor holding of lottery-like stocks in geographic regions where different attitudes towards gambling are prevalent due to different religions. Han and Kumar ( 2013 ) provide further support for the lottery-preference theory empirically. They find that stocks with high retail trade proportion have lottery-like features and earn low alphas. Bali et al. ( 2011 ) directly test the proposal that lottery preferences cause low-risk anomalies. They create decile stock portfolios based on their maximum daily return over the past month. They find that stocks with the highest past maximum daily returns significantly underperform those with the lowest past maximum daily return. Though similar in construction, they show that when controlling for their factor that selects stocks based on past maximum daily returns the low-risk anomaly measured by IV diminishes. In summary, they attribute their finding to investors willingness to overpay for stocks that may exhibit extreme positive returns. Bali et al. ( 2017 ) use the same framework to explain the return anomaly of stocks sorted on beta. In their analysis they conclude that the beta anomaly is a manifestation of the effect of lottery demand on stock returns. More empirical support for this claim is gathered by Asness et al. ( 2019 ) who decompose the BAB factor into its correlation and variance components. They proxy lottery demand with a factor portfolio that is built as a long-short portfolio based on maximum return divided by volatility. In doing so, they confirm that parts of the low-risk factor returns can be attributed to lottery demand. The preference for lottery-like payoffs is also documented by Moskowitz and Vasudevan ( 2022 ) in sports betting markets. The authors argue that since betting markets are not prone to systematic risk, only the behavioral preference of lottery like payoffs can explain the existence of the low-risk anomaly in betting and financial markets. A more comprehensive overview of lottery preferences with more examples is provided by Ilmanen ( 2012 ).

4.5 Agency problems

Same as for behavioral biases, the literature on agency problems is relatively wide and many issues can be related to the low-risk anomaly. Again, I will only present the most commonly referred to explanations, benchmarks and option-like reward systems.

4.5.1 Benchmarks

Benchmarks are argued to cause the low-risk anomaly because relative performance becomes more important than absolute performance in presence of a benchmark. Sensoy ( 2009 ) reports that in the US 94.6% of mutual funds are benchmarked to some popular index in the US. In an effort to beat benchmarks, fund managers tend to increase their exposure to stocks with a beta above one because most of them cannot take on leverage directly. Doing so, they can beat their benchmark, while aiming to maintain relatively low tracking errors. As a result, riskier stocks are overpriced and earn lower returns (Christoffersen and Simutin 2017 ; Baker et al. 2011 ). Cornell ( 2009 ) develops a model that incorporates this idea. He finds that in particular, a benchmark makes institutional investment managers less likely to exploit the low-volatility anomaly. Karceski ( 2002 ) takes the opposite view on the problem and focuses on the mutual fund investor. He shows that investors evaluate performance of mutual funds cross-sectionally and care more about the outperformance of funds in bull markets than about their underperformance in bear markets. As a result, fund managers care the most about outperforming their peers in bull markets. This can most easily be done via increasing the risk of the fund’s investments, causing overpricing of risky assets.

4.5.2 Option-like reward system

Another agency issue that incentivizes mutual fund managers to strive for riskier stocks is their reward system. Baker et al. ( 2011 ) argue that as most fund managers’ remuneration is directly linked to the fund’s performance, they have an incentive to increase risk. Hsu et al. ( 2013 ) make a similar argument for analysts. They state that analysts inflate earnings forecasts more aggressively for volatile stocks, in part because the inflation is more difficult for investors to detect. They do so because they have a similar incentive to stand out, just as fund managers. To make a career analysts also have to identify the highest-performing stocks and outperform their peers.

Evidence for the claims can be found in empirical studies. It is documented that mutual funds are tilted toward smaller stocks with higher volatility and average betas above one. In other words, they have consistent negative exposure toward the low-risk anomaly (Sias 1996 ; Frazzini and Pedersen 2014 ; Beveratos et al. 2017 ; Ang et al. 2017 ). Relatedly, Agarwal et al. ( 2022 ) find that smaller, younger mutual funds with poor recent performance own more risky stocks, arguably to attract more capital, which ultimately increases fee earnings and thus manager remuneration. Furthermore, a lab-in-the-field experiment by Kirchler et al. ( 2018 ) with a large group of investment professionals reveals that ranking and tournament incentives (that are typically present in the mutual fund industry) drive risk-taking of participants.

5 Conclusion

Before the paper can be concluded it makes sense to recapitulate on the claims made by Harvey et al. ( 2016 ) and Harvey ( 2017 ). From those the question arises whether the low-risk anomaly can be classified as an investment factor or may actually be a false positive - a non-existent factor that was is falsely believed to be relevant. Though concerns about the ever growing factor zoo are rightfully made, in light of the above review, it is rather unlikely that the low-risk anomaly is a false positive.

First, unlike other proposed risk-factors that may be exposed to p-hacking, the low-risk anomaly did not evolve from a search of potential alpha-generating factors. Instead, it was discovered from research that performed empirical studies on the predictions of the CAPM. The development of investment strategies that outperform was not the incentive of these early studies, making the storyline of the low-risk anomaly more convincing. Second, as outlined in Sect.  3 , there are multiple measures for low-risk factors that were tested across different asset classes, samples, time horizons and markets. The critique of a publication bias and degradation of performance are rightfully made but demand further investigation as results differ among studies. Third, many studies show that the effect is robust to widely accepted investment factors and other macroeconomic variables that drive asset returns. Fourth, as outlined above in Sect.  4 there are various clear economic and behavioral rationales for the findings of the empirical applications of which most are likely to persist in the future. Overall, while it is hard to deny the low-risk anomaly as an investment factor, it still can be questioned whether all its implementation methodologies have a raison d’être. The presented literature shows that most of them have exposure to the same risks and are almost indistinguishable.

Though, they strengthen the argument that the low-risk anomaly can be interpreted as a risk factor, the large number of potential explanations raises the question, which of them are the actual cause of the low-risk effect. While there are studies that attempt to disentangle the effect into its different components (Asness et al. 2019 ) more such work is required to identify the primary causes with certainty. The main problem with this task is that many proposed causes are interrelated and may result in the same phenomenon. In their literature review Blitz et al. ( 2014 ) suggest promising future research directions and methods that would help to further clarify the current root-cause problem.

Overall, it can be concluded that low-risk factors in asset returns are a widely researched area of finance. Unlike other factors, various implementation methodologies and causes have been identified by current literature. This paper provides a structured overview of current findings focusing on models and methods employed. It shows that the factor is predominantly measured via market beta, idiosyncratic volatility, total return volatility or the minimum variance portfolio in equity markets. In bond markets, it is implemented by filtering for low maturity and creditworthy bonds. The proposed causes for the anomaly include exposure to other factors, coskewness risk, investor constraints, behavioral biases, and agency problems. The low-risk anomaly as such appears to be pretty robust given its empirical evidence in various markets despite some critical voices regarding its replication and independence from other investment factors. Regarding its causes however, it still has to be validated which one of the proposed reasons prevails the most. Future research in this direction is faced with the intricate task to disentangle the different roots of the problem but could help to further understand what ultimately causes the low risk anomaly.

They use a variety of BARRA risk models depending on the availability and robustness throughout time for the different equity markets covered in the analysis. BARRA risk models are multi-factor models based on the concept of (Rosenberg 1974 ) that are used to forecast a security’s risk.

Adhami, S., Gianfrate, G., Johan, S.A.: Risks and returns in crowdlending. Eurasian. Bus. Rev. 13 , 309–340 (2023)

Adrian, T., Etula, E., Muir, T.: Financial intermediaries and the cross-section of asset returns. J. Financ. 69 (6), 2557–2596 (2014)

Article   Google Scholar  

Agarwal, V., Jiang, L., Wen, Q.: Why do mutual funds hold lottery stocks? J. Financ. Quant. Anal. 57 (3), 825–856 (2022)

Ang, A., Hodrick, R.J., Xing, Y., Zhang, X.: The cross-section of volatility and expected returns. J. Financ. 61 (1), 259–299 (2006)

Ang, A., Hodrick, R.J., Xing, Y., Zhang, X.: High idiosyncratic volatility and low returns: international and further U.S evidence. J. Financ. Econ. 91 (1), 1–23 (2009)

Ang, A., Madhavan, A., Sobczyk, A.: Crowding, capacity, and valuation of minimum volatility strategies. J. Index Invest. 7 (4), 41–50 (2017)

Asness, C.S., Frazzini, A., Gormsen, N.J., Pedersen, L.H.: Betting against correlation: testing theories of the low-risk effect. J. Financ. Econ. 135 (3), 629–652 (2019)

Asness, C.S., Frazzini, A., Pedersen, L.H.: Leverage aversion and risk parity. Financ. Anal. J. 68 (1), 47–59 (2012)

Asness, C.S., Frazzini, A., Pedersen, L.H.: Low-risk investing without industry bets. Financ. Anal. J. 70 (4), 24–41 (2014)

Asness, C.S., Frazzini, A., Pedersen, L.H.: Quality minus junk. Rev. Acc. Stud. 24 , 34–112 (2018)

Asness, C.S., Ilmanen, A., Israel, R., Moskowitz, T.J.: Investing with style. J. Invest. Manag. 13 (1), 27–63 (2014)

Google Scholar  

Auer, B.R., Schuhmacher, F.: Liquid betting against beta in dow jones industrial average stocks. Financ. Anal. J. 71 (6), 30–43 (2015)

Aussenegg, W., Götz, L., Jelic, R.M.: Common factors in the performance of European corporate bonds—evidence before and after financial crisis. Eur. Financ. Manag. 21 (2), 265–308 (2015)

Baker, M., Bradley, B., Taliaferro, R.: The low-risk anomaly: a decomposition into micro and macro effects. Financ. Anal. J. 70 (2), 43–58 (2014)

Baker, M., Bradley, B., Wurgler, J.: Benchmarks as limits to arbitrage: understanding the low volatility anomaly. Financ. Anal. J. 67 (1), 40–54 (2011)

Baker, M., Wurgler, J.: Investor sentiment and the cross-section of stock returns. J. Financ. 61 (4), 1645–1680 (2006)

Baker, N.L., Haugen, R.A.: Low risk stocks outperform within all observable markets of the world. SSRN Electron. J. (2012)

Bali, T.G., Brown, S.J., Murray, S., Tang, Y.: A lottery-demand-based explanation of the beta anomaly. J. Financ. Quant. Anal. 52 (6), 2369–2397 (2017)

Bali, T.G., Cakici, N.: Idiosyncratic volatility and the cross section of expected returns. J. Financ. Quant. Anal. 43 (1), 29–58 (2008)

Bali, T.G., Cakici, N., Whitelaw, R.F.: Maxing out: stocks as lotteries and the cross-section of expected returns. J. Financ. Econ. 99 (2), 427–446 (2011)

Bali, T.G., Del Viva, L., Lambertides, N., Trigeorgis, L.: Growth options and related stock market anomalies: profitability, distress, lotteryness, and volatility. J. Financ. Quant. Anal. 55 (7), 2150–2180 (2020)

Barber, B.M., Odean, T.: Trading is hazardous to your wealth: the common stock investment performance of individual investors. J. Financ. 55 (2), 773–806 (2000)

Barber, B.M., Odean, T.: Boys will be boys: gender, overconfidence, and common stock investment. Q. J. Econ. 116 (1), 261–292 (2001)

Barber, B.M., Odean, T.: Online investors : do the slow die first? Rev. Financ. Stud. 15 (2), 455–487 (2002)

Barber, B.M., Odean, T.: All that glitters: the effect of attention and news on the buying behavior of individual and institutional investors. Rev. Financ. Stud. 21 (2), 785–818 (2008)

Barberis, N., Huang, M.: Stocks as lotteries: the implications of probability weighting for security prices. Am. Econ. Rev. 98 (5), 2066–2100 (2008)

Barinov, A., Chabakauri, G.: Idiosyncratic volatility, growth options, and the cross-section of returns. SSRN Electron. J. (2021)

Basu, S.: Investment performance of common stocks in relation to their price-earnings ratios : a test of the efficient market hypothesis. J. Financ. 32 (3), 663–682 (1977)

Beveratos, A., Bouchaud, J.-P., Ciliberti, S., Laloux, L., Lempérière, Y., Potters, M., Simon, G.: Deconstructing the low-vol anomaly. J. Portf. Manag. 44 (1), 91–103 (2017)

Bhamra, H.S., Shim, K.H.: Stochastic idiosyncratic cash flow risk and real options: implications for stock returns. J. Econ. Theory 168 , 400–431 (2017)

Black, F.: Capital market equilibrium with restricted borrowing. J. Bus. 45 (3), 444–455 (1972)

Black, F.: Beta and return: announcements of the ‘death of beta’ seem premature. J. Portf. Manag. 20 (1), 8–18 (1993)

Black, F., Jensen, M., Scholes, M.: The capital asset pricing model: some empirical tests. In: Jensen, M. (ed.) Studies in the Theory of Capital Markets, pp. 79–121. Praeger (1972)

Blitz, D., Falkenstein, E., van Vliet, P.: Explanations for the volatility effect: an overview based on the CAPM assumptions. J. Portf. Manag. 40 (3), 61–76 (2014)

Blitz, D., Pang, J., van Vliet, P.: The volatility effect in emerging markets. Emerg. Mark. Rev. 16 (1), 31–45 (2013)

Blitz, D., van Vliet, P.: The volatility effect. J. Portf. Manag. 34 (1), 102–113 (2007)

Blitz, D., van Vliet, P., Baltussen, G.: The volatility effect revisited. J. Portf. Manag. 46 (2), 45–63 (2020)

Boguth, O., Carlson, M., Fisher, A., Simutin, M.: Conditional risk and performance evaluation: volatility timing, overconditioning, and new estimates of momentum alphas. J. Financ. Econ. 102 (2), 363–389 (2011)

Boguth, O., Simutin, M.: Leverage constraints and asset prices: insights from mutual fund risk taking. J. Financ. Econ. 127 (2), 325–341 (2018)

Boyer, B., Mitton, T., Vorkink, K.: Expected idiosyncratic skewness. Rev. Financ. Stud. 23 (1), 170–202 (2010)

Brennan, M.J.: Capital market equilibrium with divergent borrowing and lending rates. J. Financ. Quant. Anal. 6 (5), 1197–1205 (1971)

Brooks, J., Palhares, D., Richardson, S.: Style investing in fixed income. J. Portf. Manag. 44 (4), 127–139 (2018)

Brunnermeier, M.K., Gollier, C., Parker, J.A.: Optimal beliefs, asset prices, and the preference for skewed returns. Am. Econ. Rev. 97 (2), 159–165 (2007)

Brunnermeier, M.K., Parker, J.A.: Optimal expectations. Am. Econ. Rev. 95 (4), 1092–1118 (2005)

Cao, J., Han, B.: Cross section of option returns and idiosyncratic stock volatility. J. Financ. Econ. 108 (1), 231–249 (2013)

Carhart, M.M.: On persistence in mutual fund performance. J. Financ. 52 (1), 57–82 (1997)

Cederburg, S., O’Doherty, M.S.: Does it pay to bet against beta? On the conditional performance of the beta anomaly. J. Financ. 71 (2), 737–774 (2016)

Chen, A., Pong, E., Wang, Y.: Accessing the china a-shares market via minimum-variance investing. J. Portf. Manag. 45 (1), 106–117 (2018)

Chen, J., Hong, H., Stein, J.C.: Forecasting crashes: trading volume, past returns, and conditional skewness in stock prices. J. Financ. Econ. 61 (3), 345–381 (2001)

Chen, J., Hong, H., Stein, J.C.: Breadth of ownership and stock returns. J. Financ. Econ. 66 (2–3), 171–205 (2002)

Chen, L.H., Jiang, G.J., Xu, D.D., Yao, T.: Dissecting the idiosyncratic volatility anomaly. J. Empir. Financ. 59 , 193–209 (2020)

Chen, Z., Petkova, R.: Does idiosyncratic volatility proxy for risk exposure? Rev. Financ. Stud. 25 (9), 2745–2787 (2012)

Chow, T.-M., Hsu, J.C., Kuo, L.-L., Li, F.: A study of low-volatility. J. Portf. Manag. 40 (4), 89–105 (2014)

Christoffersen, S.E.K., Simutin, M.: On the demand for high-beta stocks: evidence from mutual funds. Rev. Financ. Stud. 30 (8), 2596–2620 (2017)

Chung, K.H., Wang, J., Wu, C.: Volatility and the cross-section of corporate bond returns. J. Financ. Econ. 133 (2), 397–417 (2019)

Clarke, R., de Silva, H., Thorley, S.: Minimum-variance portfolios in the U.S. equity market. J. Portf. Manag. 33 (1), 10–12 (2006)

Clarke, R., de Silva, H., Thorley, S.: Know your VMS exposure. J. Portf. Manag. 36 (2), 52–59 (2010)

Clarke, R., de Silva, H., Thorley, S.: Minimum-variance portfolio composition. J. Portf. Manag. 37 (2), 31–45 (2011)

Connor, G., Korajczyk, R.A.: Risk and return in equilibrium APT: application of a new test methodology. J. Financ. Econ. 21 (2), 255–289 (1988)

Cornell, B.: The pricing of volatility and skewness: a new interpretation. J. Invest. 18 (3), 27–30 (2009)

Danielsen, B.R., Sorescu, S.M.: Why do option introductions depress stock prices? A study of diminishing short sale constraints. J. Financ. Quant. Anal. 36 (4), 451–484 (2001)

De Carvalho, R.L., Dugnolle, P., Xiao, L., Moulin, P.: Low-risk anomalies in global fixed income: evidence from major broad markets. J. Fixed Income 23 (4), 51–70 (2014)

De Carvalho, R.L., Lu, X., Moulin, P.: Demystifying equity risk—based strategies: a simple. J. Portf. Manag. 38 (3), 56–70 (2012)

De Franco, C., Monnier, B., Rulik, K.: Interest rate exposure of volatility portfolios. J. Index Invest. 8 (2), 53–67 (2017)

De Santis, G., Gerard, B.: International asset pricing and portfolio diversification with time-varying risk. J. Financ. 52 , 1881–1912 (1997)

Derwall, J., Huij, J., de Zwart, G. J.: The Short-Term Corporate Bond Anomaly. SSRN Electronic Journal. (2009)

Dieter, K.B., Malloy, J.C., Scherbina, A.: Differences of opinion and the cross section of stock returns. J. Financ. 57 (5), 2113–2141 (2002)

Dimson, E., Marsh, P., Staunton, M.: Factor-based investing: the long-term evidence. J. Portf. Manag. 43 (5), 15–37 (2017)

Duffie, D., Gârleanu, N., Pedersen, L.H.: Securities lending, shorting, and pricing. J. Financ. Econ. 66 (2–3), 307–339 (2002)

Durham, J.B.: Betting against beta with bonds: Worry or love the steepener? Financ. Anal. J. 72 (6), 57–85 (2016)

Eraker, B., Ready, M.: Do investors overpay for stocks with lotterylike payoffs? An examination of the returns of OTC stocks. J. Financ. Econ. 115 (3), 486–504 (2015)

Falkenstein, E.G.: Risk and return in general: theory and evidence. SSRN Electron. J. (2010)

Fama, E.F., French, K.R.: The cross-section of expected stock returns. J. Financ. 47 (2), 427–465 (1992)

Fama, E.F., French, K.R.: Dissecting anomalies with a five-factor model. Rev. Financ. Stud. 29 (1), 69–103 (2016)

Fama, E.F., MacBeth, J.: Risk, return and equilibrium: empirical tests. J. Polit. Econ. 81 (3), 637–697 (1973)

Figlewski, S.: The informational effects of restrictions on short sales: some empirical evidence. J. Financ. Quant. Anal. 16 (4), 463–476 (1981)

Fink, J.D., Fink, K.E., He, H.: Expected idiosyncratic volatility measures and expected returns. Financ. Manage. 41 (3), 519–553 (2012)

Fischhoff, B., Slovic, P., Lichtenstein, S.: Knowing with certainty: the appropriateness of extreme confidence. J. Exp. Psychol. 3 (4), 552–564 (1977)

Frazzini, A., Pedersen, L.H.: Betting against beta. J. Financ. Econ. 111 (1), 1–25 (2014)

Frazzini, A., Pedersen, L.H.: Embedded leverage. Rev. Asset Pric. Stud. 12 (1), 1–52 (2022)

Friend, I., Blume, M.: Measurement of portfolio performance under uncertainty. Am. Econ. Rev. 60 (4), 561–575 (1970)

Fu, F.: Idiosyncratic risk and the cross-section of expected stock returns. J. Financ. Econ. 91 (1), 24–37 (2009)

Gebhardt, W.R., Lee, C.M., Swaminathan, B.: Toward an implied cost of capital. J. Account. Res. 39 (1), 135–176 (2001)

Grullon, G., Kanatas, G., Weston, J.P.: Advertising, breadth of ownership, and liquidity. Rev. Financ. Stud. 17 (2), 439–461 (2004)

Guo, H., Kassa, H., Ferguson, M.F.: On the relation between EGARCH idiosyncratic volatility and expected stock returns. J. Financ. Quant. Anal. 49 (1), 271–296 (2014)

Han, B., Kumar, A.: Speculative retail trading and asset prices. J. Financ. Quant. Anal. 48 (2), 377–404 (2013)

Han, X., Li, K., Li, Y.: Investor overconfidence and the security market line: new evidence from China. J. Econ. Dyn. Control 117 , 103961 (2020)

Han, Y., Hu, T., Lesmond, D.A.: Liquidity biases and the pricing of cross-sectional idiosyncratic volatility around the world. J. Financ. Quant. Anal. 50 (6), 1269–1292 (2015)

Harvey, C.R.: Presidential address: the scientific outlook in financial economics. J. Financ. 72 (4), 1399–1440 (2017)

Harvey, C.R., Liu, Y., Zhu, H.: ... and the cross-section of expected returns. Rev. Financ. Stud. 29 (1), 5–68 (2016)

Harvey, C.R., Siddique, A.: Conditional skewness in asset pricing tests. J. Financ. 55 (3), 1263–1295 (2000)

Haugen, R.A., Baker, N.L.: The efficient market inefficiency of capitalization-weighted stock portfolios. J. Portf. Manag. 17 (3), 35–40 (1991)

Haugen, R.A., Baker, N.L.: Commonality in the determinants of expected stock returns. J. Financ. Econ. 41 (3), 401–439 (1996)

Haugen, R.A., Heins, A.J.: Risk and the rate of return on financial assets: some old wine in new bottles. J. Financ. Quant. Anal. 10 (5), 775–784 (1975)

Hong, H., Sraer, D.A.: Speculative betas. J. Financ. 71 (5), 2095–2144 (2016)

Hou, K., Xue, C., Zhang, L.: Replicating anomalies. Rev. Financ. Stud. 33 (5), 2019–2133 (2020)

Houweling, P., van Zundert, J.: Factor investing in the corporate bond market. Financ. Anal. J. 73 (2), 100–115 (2017)

Hsu, J.C., Kudoh, H., Yamada, T.: When sell-side analysts meet high-volatility stocks: an alternative explanation for the low-volatility puzzle. J. Invest. Manag. 11 (2), 28–46 (2013)

Huang, W., Liu, Q., Rhee, S.G., Zhang, L.: Return reversals, idiosyncratic risk, and expected returns. Rev. Financ. Stud. 23 (1), 147–168 (2010)

Ilmanen, A.: Do financial markets reward buying or seliing insurance and lottery tickets? Financ. Anal. J. 68 (5), 2012 (2012)

Ilmanen, A., Byrne, R., Gunasekera, H., Minikin, R.: Which risks have been best rewarded? J. Portf. Manag. 30 (2), 53–57 (2004)

Israel, R., Palhares, D., Richardson, S.A.: Common factors in corporate bond returns. J. Invest. Manag. 16 (2), 17–46 (2018)

Jagannathan, R., Ma, T.: Risk reduction in large portfolios: why imposing the wrong constraints helps. J. Financ. 58 (4), 1651–1683 (2003)

Jegadeesh, N., Titman, S.: Returns to buying winners and selling losers: implications for stock market efficiency. J. Financ. 48 (1), 65–91 (1993)

Jensen, T.I., Kelly, B.T., Pedersen, L.H.: Is there a replication crisis in finance? NBER Working Paper Series, w28432 (2022)

Johnson, T.C.: Forecast dispersion and the cross section of expected returns. J. Financ. 59 (5), 1957–1978 (2004)

Jordan, B.D., Riley, T.B.: Volatility and mutual fund manager skill. J. Financ. Econ. 118 (2), 289–298 (2015)

Joshipura, N., Joshipura, M.: The volatility effect: evidence from Indian markets. Appl. Financ. Lett. 5 (1), 12–17 (2016)

Joshipura, N., Joshipura, M.: The volatility effect: recent evidence from Indian markets. Theor. Econ. Lett. 09 (06), 2152–2164 (2019)

Jylhä, P.: Margin requirements and the security market line. J. Financ. 73 (3), 1281–1321 (2018)

Kahneman, D., Tversky, A.: On the psychology of prediction. Psychol. Rev. 80 (4), 237–251 (1973)

Kahneman, D., Tversky, A.: Prospect theory: an analysis of decision under risk. Econometrica 47 (2), 263–291 (1979)

Karceski, J.: Returns-chasing behavior, mutual funds, and beta’s death. J. Financ. Quant. Anal. 37 (4), 559–594 (2002)

Kirchler, M., Lindner, F., Weitzel, U.: Rankings and risk-taking in the finance industry. J. Financ. 73 (5), 2271–2302 (2018)

Kothe, J., Lohre, H., Rother, C.: Rates factors and global asset allocation. J. Fixed Income 30 (3), 6–25 (2021)

Kraus, A., Litzenberger, R.H.: Skewness preference and the valuation of risk assets. J. Financ. 31 (4), 1085–1100 (1976)

Kumar, A.: Who gambles in the stock market? J. Financ. 64 (4), 1889–1933 (2009)

Kumar, A., Page, J.K., Spalt, O.G.: Religious beliefs, gambling attitudes, and financial market outcomes. J. Financ. Econ. 102 (3), 671–708 (2011)

Ledoit, O., Wolf, M.: Honey, I shrunk the sample covariance matrix. J. Portf. Manag. 30 (4), 110–119 (2004)

Lintner, J.: The valuation of risk assets and the selection of risky investments in stock portfolios and capital budgets. Rev. Econ. Stat. 47 (1), 13–37 (1965)

Liu, J., Stambaugh, R.F., Yuan, Y.: Absolving beta of volatility’s effects. J. Financ. Econ. 128 (1), 1–15 (2018)

Markowitz, H.: Portfolio selection. J. Financ. 7 (1), 77–91 (1952)

Miller, E.M.: Risk, uncertainty, and divergence of opinion. J. Financ. 32 (4), 1151–1168 (1977)

Miller, E.M., Scholes, M.: Rates of return in relation to risk: a reexamination of some recent findings. In: Jensen, M. (ed.) Studies in the Theory of Capital Markets, pp. 47–78. Praeger (1972)

Morris, S.: Speculative investor behavior and learning. Q. J. Econ. 111 (4), 1111–1133 (1996)

Moskowitz, T.J., Vasudevan, K.: Betting without beta. SSRN Electron. J. (2022)

Moskowitz, T.J., Vissing-Jørgensen, A.: The returns to entrepreneurial investment: a private equity premium puzzle? Am. Econ. Rev. 92 (4), 745–778 (2002)

Mossin, J.: Equilibrium in a capital asset market. Econometrica 34 (4), 768–783 (1966)

Novy-Marx, R.: The other side of value: the gross profitability premium. J. Financ. Econ. 108 (1), 1–28 (2013)

Novy-Marx, R.: Understanding defensive equity. Natl. Bureau Econ. Res. 20591, 3 (2016)

Novy-Marx, R., Velikov, M.: Betting against betting against beta. J. Financ. Econ. 143 (1), 80–106 (2022)

Odean, T.: Do investors trade too much? Adva. Behav. Econ. 89 (5), 1279–1298 (1999)

Park, S.G., Wei, K.C.J., Zhang, L.: The Fu (2009) positive relation between idiosyncratic volatility and expected returns is due to look-ahead. Crit. Financ. Rev. (forthcoming) (2020)

Pilotte, E.A., Sterbenz, F.P.: Sharpe and treynor ratios on treasury bonds. J. Bus. 79 (1), 149–180 (2006)

Pyun, C.: Documenting the post-2000 decline in the idiosyncratic volatility effect. Crit. Financ. Rev. 10 (3), 419–427 (2021)

Rosenberg, B.: Extra-market components of covariance in security returns. J. Financ. 9 (2), 263–274 (1974)

Rubinstein, M.: The fundamental theorem of parameter-preference security valuation. J. Financ. Quant. Anal. 8 (1), 61–69 (1973)

Scherer, B.: A note on the returns from minimum variance investing. J. Empir. Financ. 18 (4), 652–660 (2011)

Schneider, P. G., Trojani, F.: Fear Trading. Swiss Finance Institute Research Paper. 15–03 (2015)

Schneider, P.G., Wagner, C., Zechner, J.: Low-risk anomalies? J. Financ. 75 (5), 2673–2718 (2020)

Sensoy, B.: Performance evaluation and self- designated benchmark indexes in the mutual fund management industry. J. Financ. Econ. 92 (1), 25–39 (2009)

Sharpe, W.F.: Capital asset prices: a theory of market equilibrium under conditions of risk. J. Financ. 19 (3), 425–442 (1964)

Sias, R.W.: Volatility and the institutional investor. Financ. Anal. J. 52 (2), 13–20 (1996)

Soe, A.M.: Low-volatility portfolio construction: ranking versus optimization. J. Portf. Manag. 2 (3), 63–73 (2012)

Stambaugh, R.F., Yu, J., Yuan, Y.U.: Arbitrage asymmetry and the idiosyncratic volatility puzzle. J. Financ. 70 (5), 1903–1948 (2015)

Treynor, J.L.: Market value, time, and risk (unpublished manuscript) (1961)

Tversky, A., Kahneman, D.: Advances in prospect theory: cumulative representation of uncertainty. Springer 5 (4), 297–323 (1992)

Walkshäusl, C.: International low-risk investing. J. Portf. Manag. 41 (1), 45–56 (2014)

Zaremba, A., Czapkiewicz, A.: The cross section of international government bond returns. Econ. Model. 66 , 171–183 (2017)

Download references

Acknowledgements

I am grateful to an anonymous referee as well as Manuel Ammann, Markus Schmid, Kevin Schneider and participants at the “Topics in Asset Management” Ph.D. seminar at the University of St. Gallen for their comments on an earlier version of this paper.

Open access funding provided by University of St.Gallen

Author information

Authors and affiliations.

Swiss Institute of Banking and Finance, University of St. Gallen, Unterer Graben 21, 9000, St. Gallen, Switzerland

Joshua Traut

You can also search for this author in PubMed   Google Scholar

Corresponding author

Correspondence to Joshua Traut .

Additional information

Publisher's note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ .

Reprints and permissions

About this article

Traut, J. What we know about the low-risk anomaly: a literature review. Financ Mark Portf Manag 37 , 297–324 (2023). https://doi.org/10.1007/s11408-023-00427-0

Download citation

Accepted : 26 January 2023

Published : 28 April 2023

Issue Date : September 2023

DOI : https://doi.org/10.1007/s11408-023-00427-0

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• Factor investing
• Asset pricing
• Style investing

JEL Classification

• Find a journal
• Publish with us
• Track your research

Help | Advanced Search

Computer Science > Human-Computer Interaction

Title: apprentices to research assistants: advancing research with large language models.

Abstract: Large Language Models (LLMs) have emerged as powerful tools in various research domains. This article examines their potential through a literature review and firsthand experimentation. While LLMs offer benefits like cost-effectiveness and efficiency, challenges such as prompt tuning, biases, and subjectivity must be addressed. The study presents insights from experiments utilizing LLMs for qualitative analysis, highlighting successes and limitations. Additionally, it discusses strategies for mitigating challenges, such as prompt optimization techniques and leveraging human expertise. This study aligns with the 'LLMs as Research Tools' workshop's focus on integrating LLMs into HCI data work critically and ethically. By addressing both opportunities and challenges, our work contributes to the ongoing dialogue on their responsible application in research.

Submission history

Access paper:.

• HTML (experimental)
• Other Formats

References & Citations

• Google Scholar
• Semantic Scholar

BibTeX formatted citation

Bibliographic and Citation Tools

Code, data and media associated with this article, recommenders and search tools.

• Institution

arXivLabs: experimental projects with community collaborators

arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website.

Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them.

Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs .