Up until this point, this OER has taken us through the parts of the research journey that involve identifying our worldview and the theories that fall within it and how to move from general topics of interest within that framework to specific, feasible research questions that can be answered empirically. We have emphasized the importance of ethics at each of these phases.

The next step is to delve into the work that has already been done by others on or related to our chosen research question. This chapter begins by defining what a literature review is and outlining the steps involved in conducting such a review. Then, more detailed instruction is provided on how to conduct a good review of the literature and how to properly reference the work of others while doing so. The importance of conducting a thorough and focused literature review cannot be emphasized enough. After all, it is sometimes easiest to decide where to go when we’ve learned where we have already been.

What is a Literature Review?

A literature review is a comprehensive survey of what has been written about a particular topic, theory, or research question. Think about “literature” as “sources of information” that can include peer-reviewed sources like academic journal articles and books as well as grey literature like government reports, policy documents, speeches, or working papers. This literature will inform you about the research that has already been conducted on your chosen subject to support the development of your own study. A literature review can serve as a background for a larger work (e.g., as part of a research proposal or journal article), or it may stand on its own. Much more than a simple list of sources, an effective literature review analyzes and synthesizes information around key themes or issues.

Purpose of a Literature Review

A literature review involves an extensive study of research publications, books and other documents related to your defined problem or research question. The review of existing research advises you, as a researcher, as to whether the problem you have identified has already been addressed by other researchers and the methodologies these researchers used to address their own research questions. This information is important because we do not want to repeat research that has already been done unless there is a good reason for doing so (i.e., examining a new development in this area, testing a theory with a new population, or even just seeing if the research can be reproduced). A literature review also evaluates the status of the problem or issue, any debates or disagreements in the literature, or other related details.

A literature review goes beyond the search for information; it includes the identification and articulation of relationships between existing literature and your field of research. The literature review enables the researcher to discover what material exists about a topic and to understand the relationship between the various contributions. For example, within the literature on gender-based violence, there is a debate over whether men and women are equally violent in intimate relationships (Fanslow, Mellar, Gulliver, McIntosh, 2023; Hamby, 2014; Hardesty & Ogolsky, 2020). One side of the debate argues that there is symmetry in the violence and abuse between partners, while the other side of the debate holds that there is a gender imbalance, with men predominately the aggressors and women the victims of relationship violence. A comprehensive review of the literature reveals these points of difference, which enables the researcher to identify and (if possible) resolve contradictions as well as determine research gaps and/or unanswered questions.

Even though the nature of the literature review may vary with different types of studies, the basic purposes remain constant and can be summarized as follows:

• Provide a context for your own research and justify the research you are proposing. The literature helps you answer the ‘so what?’ question about why your research is important.
• Show where your proposed research fits into the existing body of knowledge and can add to the understanding and knowledge of the field. A strong literature review will outline potential gaps in knowledge and thus help articulate what your research adds to the overall literature.
• Identify whether your proposed research has been carried out by another researcher (and if it has, the literature review should help specify why replication is necessary).
• Illustrate the methodological approaches used to study the subject. Understanding how others approached the issue can offer ideas on how you could address your own research question as well as help justify your proposed method.
• Highlight challenges in previous research. These challenges could be methodological or theoretical; for example, the perspectives of a specific group impacted by the issue may be missing or an application of a particular theory to a problem may be incomplete.
• Help refine or refocus the topic or even move it in a new direction.

What is Involved in Writing a Literature Review?

Generally, a literature review is conducted in three steps:

• Research – to discover what has been written about the topic;
• Critical evaluation – to evaluate the literature, determine the relationship between the sources, ascertain what has been done already and what still needs to be done; and
• Writing – to explain what you have found.

It is often helpful to think of the literature review as a funnel or an inverted pyramid, moving from very broad general sources to very specific questions. More specifically, you start with a broad examination of the research related to the topic, working down to look at more specific aspects of the topic, which leads to the gap or the specific aspect of the topic your research question will address, as seen in Figure 5.1.

How to Undertake a Literature Review

The first step in undertaking a literature review is to conduct a search of peer-reviewed academic research that has been done on your topic. With the variety of databases electronically available through university libraries, there are millions of scholarly sources accessible from your keyboard. Google Scholar is also a good tool for your search as is the practice of consulting a librarian. Regardless of the database or site you use, it is good practice to evaluate whether the source you find is peer-reviewed, grey literature, or another type of source (see Table 5.1). Grey literature – research conducted outside academia – can serve as an important research source for your literature review. Indeed, such research can have important practical and policy implications, as academic research can sometimes tend toward more theoretical applications.

At this stage, you will likely skim the sources to see if they are relevant for your literature review and for your research question. Not every journal article will be applicable or useful, but it is often important to read more than just the title and abstract (though these can be helpful)!

Part of evaluating the sources is not just assessing whether the source is peer-reviewed or grey literature. It is important to understand who completed the research, the type of research or method used, who funded or sponsored the research you review, in addition to the perspective and purpose of the research. For example, much of the research in the social sciences is funded by the Government of Canada through the Social Sciences and Humanities Research Council. However, researchers are increasingly turning to industry and private grants to fund their research, which may shape the lens through which the research is communicated.

Another critical aspect to consider as you are collecting your sources is related to authorship and citation bias. Citation bias can occur in a few ways: a geographical bias can exist in which sources from one region are marginalized or cited more (e.g., North American studies are overwhelmingly included while other regions are excluded), or a gender or race bias may exist where research by women and racialized researchers is minimally cited or ignored (Calderón, 2022; Chakravartty, Kuo, Grubbs, & McIlwain, 2018; Gewin, 2021; Pandey & Burch-Smith, 2024). There can be valid reasons for taking a geographical focus; for example, if you are researching community policing in Canada, it would make sense to focus on Canadian research. Within this focus you would want to include writings on First Nations research and efforts around the topic. Actively recognizing and resisting citation bias is a crucial part of our collective efforts to decolonize research. One way researchers can do this is by remaining alert to the potential for citation bias in their own work and by seeking out and including the research and work of marginalized researchers as part of a comprehensive literature review.

There are a few more things to keep in mind in this first step as you review the literature:

• Who are the various researchers who have studied this topic? Who are the most prolific researchers/writers on this topic? Has a specific researcher or team of researchers been identified as pioneers or leaders in this field of study?
• How have the various researchers defined key terms that are relevant to your topic? Have the definitions of any of the key terms evolved over time?
• What are the different theories that have been examined and applied to this topic? How, if at all, have the various theories applied to this topic evolved over time?
• What methodologies have been used to study this topic? Have these methodologies evolved over time?

As you compile your list of sources, be aware that you will likely not include all the resources you have read in your final literature review. A good general guideline for the ‘search’ stage is to read 1.5 times as many sources as you are required to include in your assignment. If you are asked to include 20 resources in your literature review, expect to read approximately 30 to find the best 20. Table 5.1 offers some examples of sources you could include in a literature review, encompassing scholarly material, grey literature, and other sources.

The second step in the process is the critical evaluation of the sources you have gathered. It is often beneficial to first read or skim the whole article, look away, and ask yourself what you felt was the main idea before jumping into a deeper reading of the source. In addition to thinking about the questions noted above, you should be taking notes during this process. There are a variety of ways to organize your notes, but you should include the following information:

• Citation: A full citation of the source to help you ensure proper referencing and a complete reference list.
• Research question: The research question or main points of the research. This includes any hypotheses the researchers propose. If the article is a review of previous research, look for the main points.
• Theory: The theoretical framework and any major concepts the research uses. For example, if the research uses a specific theory to explain the issue or an operational definition, this is handy information to note.
• Methods: The methodology used for the research, such as a qualitative or quantitative approach, the method of data collection, details of the sample (e.g., the number of participants, who they are), and analysis process.
• Results: The results or main findings of the study. Writing down the results of the study in your own words in a few sentences is a good idea. For example, “people who are between the ages of 18 and 35 are more likely to own a smartphone than those in an age range above or below.”
• Conclusion: The conclusion of the research or, in other words, the ‘answer’ to the research question. It is also helpful to identify the implications and/or recommendations of the authors, which are typically noted in the conclusion, as this can point to gaps in knowledge or policy.
• Pros/cons: The strengths and limitations of the research. Most articles will identify limitations, but you should think beyond what the authors state to consider limitations for your own research question and the literature overall. Also, think about the strengths of the source in terms of what it adds to knowledge or methodological strengths such as including an underrepresented group.
• Other: Anything else you find interesting, questions you may have about the particular source, or contradictions with other sources.

See this literature review matrix [DOC] for a concrete example of how some of this information can be organized in a meaningful and useful format.

When reading through and evaluating your sources, remember that you are looking for the “big picture,” not a collection of random, separate articles (an annotated bibliography). You are also not trying to prove a point (an essay). You are looking for common themes and patterns in the research as a whole. You are also looking to see how the various pieces of research are linked, if at all, in the overall body of literature. You cannot be expected to be an expert on your topic at this stage in your academic career, but you do need to be able to identify gaps in the research on your topic. A tip for finding gaps is to read the conclusion section of the sources your search has uncovered, as researchers often identify such gaps as well as suggest areas for future research as part of summarizing their research. However, if a researcher suggested a gap 10 years ago, this gap has likely now been addressed. Look at the most recent research your literature review has uncovered (suggested within 2–3 years of the current date) and compare with older articles to see how this gap has been addressed over time.

At this point in your search of the literature, you may realize that your research question needs to change or adapt. This is a common occurrence, since when you first develop a research question, you cannot be sure what the status of the research area is until you undertake your review of the literature related to this topic. You will also likely have to revisit your literature review at later stages of your research, such as when writing up your methods or analyzing your findings, so that you can connect your own research to the larger body of literature. This is very much an iterative process, as shown in Figure 5.2. Think of your literature review as a segment of your research that evolves and shifts in line with how your research unfolds. A strong foundation of a well-researched and comprehensive literature review makes such changes and revisions easier.

How to Write a Literature Review

After undertaking a search of existing research that has been done on your topic (step 1) and critically evaluating the research gathered (step 2), the next step involves taking your notes from your critical evaluation of the sources, organizing the information, and actually writing the literature review. A literature map, as illustrated in Figure 5.3, is one option to aid in organizing information before starting to write. Whatever method you use, mapping out how the literature works together in terms of themes or concepts, and which sources you are including with the themes and/or concepts, helps ensure that you are providing a review of the body of literature rather than a paper similar to an annotated bibliography (a summary of each article independently with no stated connection between them).

The Five ‘C’s of Writing a Literature Review

To help you frame and write your literature review, think about these five Cs (Callahan, 2014):

1. Cite the material you have referred to and used to help you define the research problem you will study.
2. Compare the various arguments, theories, methods, and findings expressed in the literature. For example, describe where the various researchers agree and where they disagree. Describe the similarities and dissimilarities in approaches to studying related research problems.
3. Contrast the various arguments, themes, methods, approaches, and controversies apparent and/or described in the literature. For example, describe what major areas are contested, controversial and/or still being debated.
4. Critique the literature. Describe which arguments you find more persuasive and explain why. Explain which approaches, findings, and methods seem most reliable, valid, appropriate, and/or most popular and why. Pay attention to the verbs you use to describe what previous researchers have stated (e.g., asserts, demonstrates, argues, clarifies.).
5. Connect the various research studies you reviewed. Describe how your work utilizes, draws upon, departs from, synthesizes, adds to or extends previous research studies.

There are three parts to the literature review: the introduction, the body, and the conclusion.

The introduction must identify the topic by briefly discussing the significance of the topic and offering a broad overview of the scope of the work you are reviewing. If your literature review is part of a larger work, the introduction is a good place to explain the importance of the review to your research question. You will also want to establish the scope of your literature review in the introduction, for example, whether you are looking at the entire history of the field or just a particular period of time.

In the body of the literature review, discuss and assess the research in the field based on your selected organizational technique (see Table 5.2) rather than addressing each source separately. Most, if not all, paragraphs should discuss multiple sources. Here is where you will compare, contrast, and connect the various pieces of research. For instance, if you are researching the effects of post-traumatic stress (PTS) on law enforcement officers and are taking a thematic approach to organizing your literature review, you may have mapped out themes such as the effects of PTS on sick time, effects of PTS on families of officers, and effects of PTS on overall officer wellness. You will want to connect the research within each theme, such as what different researchers have found about the effects of PTS on sick time, and contrast any differences. For another example of a literature review that takes a thematic approach, see this one conducted by one of the editors of this open education resource: Developmental Disability, Crime, and Criminal Justice: A Literature Review [PDF]. You will notice in this example that the many themes that emerge in the literature review are outlined in the introduction of the paper, guiding the reader on what to expect, and in what order.

It is best practice to use your own words while summarizing and paraphrasing the works you are reviewing. Use direct quotes sparingly and strategically; instead, illustrate your knowledge and understanding of the field of research (see this short video for the difference between summarizing, paraphrasing and using direct quotes: Quoting, Paraphrasing, & Summarizing). In your conclusion, suggest where the research in the field will or should go next. If you are proposing your own research study, show how your research question will contribute to the field and fill in any gaps. The conclusion is also a good place to defend the importance of the topic, now that you have demonstrated the current state of thinking in the field.

Table 5.2 offers three common ways to organize your literature review: thematically, methodologically, and chronologically, along with when you might want to use each technique, with examples. Remember that most college and university libraries have research and writing resources to help as well!

Literature Review, Essay, Annotated Bibliography: What’s the Difference?

Many students struggle with understanding the difference between a literature review and an essay. This often occurs because a student can use the exact same resources to create a literature review or an essay, and the format of the writing (introduction, body, conclusion) is the same. However, an essay and a literature review have different purposes.

A literature review focuses on everything that has been written about a particular topic, theory, or body of research. It is focused on the research and the researchers who have undertaken research on your topic. In contrast, an essay focuses on proving a point or supporting an argument. An essay has a narrower focus; it does not need to provide extensive coverage of all the material on the topic, and while writers may offer evidence (literature) with a contrary perspective, they mainly use those sources that prove the point. Another way to think about the difference is that a literature review raises a question from the literature (e.g., research gaps, your research question), while an essay seeks to answer a question (e.g., support your thesis or your argument) (University of Newcastle, 2020).

An annotated bibliography is a third type of academic writing that can sometimes confuse students who are attempting to write a literature review. A literature review may use the same sources, but it does so in an integrated way, using multiple sources in the same paragraph to show the breadth of research on a particular aspect of a theme or method. An annotated bibliography focuses on one source and then moves to another, with no integration between the sources. In essence, an annotated bibliography is a list with extra details about each source, providing all the reference details of a source with a short (approximately 150 words) description, or annotation, of the article, book, report, etc. The sources should be referenced in the proper format for your chosen style (APA and Chicago are two common styles in the social sciences). An annotated bibliography is not to be confused with a bibliography (or reference list), which is a list (without additional description or discussion) of journal articles, books, and other resources that someone has used and referenced in their writing (see sample annotated bibliography).

Proper Referencing and Citation

Part of good research practice is to reference each source you use in your work. The purpose of referencing your sources is to give credit where credit is due (i.e., someone else´s work) and to ensure you avoid being accused of plagiarism (i.e., putting forth someone else´s work as your own). Proper referencing includes both a formal reference list of all sources used at the end of your paper as well as citing sources used in-text as well as attributing ideas and research to the authors whose work you are drawing upon. There are many established referencing styles that provide a set of rules for writing and referencing (citing) your sources. The American Psychological Association (APA) referencing style is widely accepted in the social sciences and is the referencing style used in this text. APA has specific formats for the different reference list entries (e.g., a slightly different format for a journal article than a government report). College and university libraries will also have resources to support you in properly referencing your writing regardless of the style you adopt, and there is a wealth of online resources to use. The Online Writing Lab from Purdue University is an excellent resource. Remember, proper referencing is a key to strong and honest academic writing.

Conclusion

In this chapter, we introduced you to the comprehensive and systemic review of the existing body of knowledge on our topics of interest and research questions: the literature review. We discussed the purpose of a literature review and how to write one, with specific reference to the 5 Cs. Moving beyond just gathering sources, a review of the literature also requires us to critically evaluate and synthesize our sources. Identifying gaps within the literature when devising our own research questions is key; sometimes, we revise the research question as needed as we discover new, relevant sources of information.

Specific steps are provided in this chapter on how to go about writing a good literature review. Different ways to organize a literature review are also offered, whether it is a standalone document or offered as part of an actual research study. Last, but not least, the importance of properly referencing the sources we include in our literature review is highlighted. After all, giving credit where credit is due is part of our responsibility as ethical social science researchers.

Further Reading

• Critical criminological understandings of adult pornography and woman abuse: New progressive directions in research and theory
• Strategies to support substance use disorder care transitions from acute-care to community-based settings: a scoping review and typology
• A scoping review of school-based indigenous substance use prevention in preteens (7–13 years)
• Ravenous wolves revisited: a systematic review of offending concentration
• Factors contributing to quarter life crisis on early adulthood: A systematic literature review

References

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Callahan, J. L. (2014). Writing literature reviews: A reprise and update. Human Resource Development Review, 13(3), 271-275. https://doi.org/10.1177/1534484314536705

Chakravartty, P., Kuo, R., Grubbs, V., & McIlwain, C. (2018). #CommunicationSoWhite. Journal of Communication, 68(2), 254–266. https://doi.org/10.1093/joc/jqy003

Cronin, P., Ryan, F., & Coughlan, M. (2008). Undertaking a literature review: A step-by-step approach. British Journal of Nursing, 17(1), 38-43. https://doi.org/10.12968/bjon.2008.17.1.28059

Fanslow, J. L., Mellar, B. M., Gulliver, P. J., & McIntosh, T. K. D. (2023). Evidence of gender asymmetry in intimate partner violence experience at the population-level. Journal of Interpersonal Violence, 38(15-16), 9159–9188. https://doi.org/10.1177/08862605231163646

Gewin, V. (2021). How to include Indigenous researchers and their knowledge. Nature, 589(7841), 315–317. https://doi.org/10.1038/d41586-021-00022-1

Hamby, S. (2014). Intimate partner and sexual violence research: Scientific progress, scientific challenges, and gender. Trauma, Violence, & Abuse, 15(3), 149-158. https://doi.org/10.1177/1524838014520723

Hardesty, J. L., & Ogolsky, B. G. (2020). A socioecological perspective on intimate partner violence research: A decade in review. Journal of Marriage and Family, 82(1), 454–477. https://doi.org/10.1111/jomf.12652

Hassan, S., & Gordon, R. M. (2003). Developmental disability, crime, and criminal justice: A literature review [PDF]. Simon Fraser University, School of Criminology, Criminology Research Centre. https://www.sfu.ca/crc/fulltext/hassangordon.pdf

Pandey, S., & Burch-Smith, T. (2024) Overcoming citation bias is necessary for true inclusivity in Plant Science. The Plant Cell, 36(1),10–13. https://doi.org/10.1093/plcell/koad248

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University of Newcastle, Australia. (2020). Literature Reviews [PDF]. https://www.newcastle.edu.au/__data/assets/pdf_file/0005/827726/Literature-Reviews.pdf

Adaptation Statement

Chapter adapted from Research Methods for the Social Sciences: An Introduction by Valerie Sheppard, licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.