A literature review is a survey of everything that has been written about a particular topic, theory, or research question. The word “literature” means “sources of information”. The literature will inform you about the research that has already been conducted on your chosen subject. This 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. there has been a new development in this area or testing a theory with a new population, or even just to see if the research can be reproduced).  Literature reviews usually serve as a background for a larger work (e.g. as part of a research proposal), or it may stand on its own. Much more than a simple list of sources, an effective literature review analyzes and synthesizes information about key themes or issues.

Purpose of a literature review

The literature review involves an extensive study of research publications, books and other documents related to the defined problem.  The study is important because it advises you, as a researcher, whether the problem you identified has already been solved by other researchers.  It also advises you as to the status of the problem, techniques that have been used by other researchers to investigate the problem, and other related details.

A literature review goes beyond the search for information and includes the identification and articulation of relationships between existing literature and your field of research. The literature review enables the researcher to discover what has been already been written about a topic and to understand the relationship between the various contributions. This will enable the researcher to determine the contributions of each sources (books, article, etc.) to the topic. Literature reviews also enable the researcher to identify and (if possible) resolve contradictions, and also 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 could be summarized as follows:

• • Provide a context for your research;
  • Justify the research you are proposing;
  • Ensure that your proposed research has not been carried out by another person (and if you find it has, then your literature review should specify why replication is necessary);
  • Show where your proposed research fits into the existing body of knowledge;
  • Enable the researcher to learn from previous theory on the subject;
  • Illustrate how the subject has been studied previously;
  • Highlight flaws in previous research;
  • Outline gaps in previous research;
  • Show how your proposed research can add to the understanding and knowledge of the field;
  • Help refine, refocus, or even move the topic in a new direction

What is involved in writing a literature review?

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

Generally speaking, it is helpful to think of the literature review as a funnel.  One starts with a broad examination of the research related to the issue, working down to look at more specific aspects of the issue, which leads to the gap or the specific issue that your research will address.

How to undertake a literature review

The first step in undertaking a literature review is to conduct a library search of academic research that has been done on your topic.  This can be done electronically, or if you are within close vicinity to a library, you can go in and use their computers to find electronic and print holdings. You can also use Google Scholar for your search.  In some cases, research conducted outside academia can serve as an important research source for your literature review. Indeed, such research can have important practical implications, as opposed to academic research which usually (although not always) tends toward theoretical applications.

However, it is important to understand who funded the research you review, in addition to the perspective and the purpose of the research.  This is becoming an issue in Canada as universities and colleges increasingly turn to industry for research funding grants (see How TransAlta used a university-sanctioned research project to lobby for the coal industry).

As part of this first step there are a few more some things to be thinking about as you review the literature, as follows:

• 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 teams 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 over time evolved?
• What methodologies have been used to study this topic?  Have the methodologies evolved over time?

In addition to thinking about these questions, you should be taking notes during this process. It can be helpful to keep these notes in an Excel file.  For example, your notes should include the following information:

• If the article is empirical, write down the results of the research study in one or two sentences of your own words. e.g. “people who are between ages 18 – 35 are more likely to own a smart phone than those above or below.”  It is also a good idea to make note of the methods, the research design, the number of participants and details on the sample used in the study. Sometimes, you may even want to write down the names of the statistical procedures used to analyze the data or even some of the statistics, depending on your assignment.
• If the article is a review of previous research, look for the main points. It may be helpful to read or skim the whole article, look away, and ask yourself what you felt was the main idea.
• Write down any limitations or gaps you notice, anything that seems to contradict something you read elsewhere, or just anything that you think is important or interesting (Adjei, n.d.)

When reading through 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.  As part of this process, you also want to identify research gaps or areas that require further research related your topic (Adjei, n.d.). In this regard, you cannot be expected to be an expert on your topic. A suggestion for finding gaps is to read the conclusion section of the academic journal articles and conference proceedings your search has uncovered.  Researchers often identify gaps in the research in their conclusion. They may even suggest areas for future research. However, remember, if a researcher suggested a gap 10 years ago, it is likely that the gap has now been addressed. To find a gap, look at the most recent research your literature review has uncovered (within 2-3 years of the current date). At this point in your search of the literature, you may realize that your research question needs to change or adapt.  This is a fairly common occurrence, as 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. Finally, it is worth mentioning that it is very likely you will not include all of the resources you have read in your literature review. If you are asked to include 20 resources in your literature review, for example, expect to read approximately 30.

How to write a literature review

There are three parts to the literature review: the introduction, the body, and the conclusion.  In the following paragraphs we outline what to include in each of these sections. This section concludes with a variety of resources for you to check out.

Introduction

• The introduction must identify the topic by briefly discussing the significance of the topic including a statement that outlines the conclusion to be drawn from the literature review.
• If your literature review is part of a larger work, explain the importance of the review to your research question.
• Defend the importance of the topic by giving a broad overview of the scope of the work you are reviewing. For example, if you are interested in post traumatic stress disorder (PTSD) in paramedics, you might provide some stats to prove how much work time is lost by those suffering from PTSD.
• Clarify whether you are looking at the entire history of the field, or just a particular period of time.

Body

• Discuss and assess the research according to specific organizational principles (see examples below), rather than addressing each source separately. Most, if not all, paragraphs should discuss more than one source. Avoid addressing your sources alphabetically as this does not assist in developing the themes or key issues central to your review.
• Compare, contrast, and connect the various pieces of research. Much of the research you are reading should be connected.  Or you may notice various themes within the research (i.e. effects of PTSD on sick time, effects of PTSD on families of paramedics, effects of PTSD on overall paramedic wellness, etc.).  If you have undertaken a thorough review of the literature, you should start to see the bigger picture of how the research on this topic has evolved over time, who the main researchers are on this topic, how the methods and theories related to this topic have changed (if at all), over time.
• Summarize the works you are reviewing. Just as in any written assignment, use logical organization and clear transitions. Spend more time on the researchers and bodies of research that are considered most important in the field and/or that are most relevant.

Conclusion

Based upon your research, suggest where the research in the field will or should go next. If you are proposing your own research study, show how you will contribute to the field and fill in any gaps. The conclusion would also be a good place to defend the importance of the topic, now that you have demonstrated the current state of thinking in the field.

Other resources to help you write a literature review

In conclusion, there is a plethora of resources, both here and online, that provide information on how to write a literature review. For example, check out these three, very helpful YouTube videos prepared by a professor at the University of Maryland, in the U.S.A:

• The Literature Review, Part 1
• The Literature Review, Part 2
• The Literature Review, Part 3

Table 5.1 also provides some suggested organizational techniques, as well as instances when you might use these various techniques.  The table also provides a writing sample to demonstrate the writing technique.

And remember, most university and college libraries also have valuable information on literature reviews.  Here is the link to one such website: JIBC Literature Review information [PDF]

Acceptable sources for literature reviews

There are a few acceptable sources for literature reviews, and I will list these in order from what will be considered most acceptable to less acceptable sources for your literature review assignments, as follows:

1. Peer reviewed journal articles;
2. Edited academic books;
3. Articles in professional journals;
4. Statistical data from government websites;
5. Website material from professional associations (use sparingly and carefully);

The following sections will explain and provide examples of these various sources.

Peer reviewed journal articles (papers)

A peer reviewed journal article is a paper that has been submitted to a scholarly journal, accepted, and published.  Peer review journal papers go through a rigorous, blind review process of peer review. What this means is that two to three experts in the area of research featured in the paper have reviewed and accepted the paper for publication. The names of the author(s) who are seeking to publish the research have been removed (blind review), so as to minimize any bias towards the authors of the research. Albeit, sometimes a savvy reviewer can discern who has done the research based upon previous publications, etc.  This blind review process can be long (often 12 to 18 months) that may involve many back and forth edits on the behalf of the researchers, as they work to address the edits and concerns of the peers who reviewed their paper. Often, reviewers will reject the paper for a variety of reasons, such as unclear or questionable methods, lack of contribution to the field, etc. Because peer reviewed journal articles have gone through a rigorous process of review, they are considered to be the premier source for research. Peer reviewed journal articles should serve as the foundation for your literature review.

The following website will provide more information on peer-reviewed journal articles: Evaluating Information Sources: What Is A Peer-Reviewed Article? Make sure you watch the little video on the upper left-hand side of your screen, in addition to reading the material.

Edited academic books

An edited academic book is a collection of scholarly scientific papers written by different authors. The works are original papers, not published elsewhere (Wikipedia, 2018).  The papers within the text also go through a process of review; however, the review is often not a blind review because the authors have been invited to contribute to the book. Consequently, edited academic books are fine to use for your literature review, but you also want to ensure that your literature review contains mostly peer reviewed journal papers.

Articles in professional journals.

Articles from professional journals should be used with caution, as far as it relates to a source for your literature review.  This is because articles in trade journals are not usually peer reviewed, even though they may appear as such. A good way to find out is to read the “About us” section of the professional journal.  They should state there if the papers are peer reviewed. You can also google the name of the journal and add peer reviewed to the search and you should be able to find out that way.

Statistical data from governmental websites.

Governmental websites can be excellent sources for statistical data.  For examples, Statistics Canada collects and publishes data related to the economy, society, and the environment.

Website material from professional associations

Material from other websites can also serve as a source for statistics that you may need for your literature review.  As you want to justify the value of the research you are interested in, you might make use of a professional association´s website to learn how many members they have, for example.  As a hypothetical example, you might want to demonstrate, as part of the introduction to your literature review, why more research on the topic of PTSD in police officers is important.  You could use peer reviewed journal articles to determine the prevalence of PTSD in police officers in Canada in the last ten years and then use the Ontario Police Officers´ Association website to determine the approximate number of police officers employed in the Province of Ontario over the last ten years. This might help you create an approximation of how many police officers could be suffering with PTSD in Ontario.  That number could potentially help to justify a research grand down the road. But again, this type of website-based material should be used with caution and sparingly.

Text Attributions

• This chapter has been adapted from Unit 2: Literature Review in Research Methods by Joseph K. Adjei. © Creative Commons Attribution-ShareAlike 3.0 License.