How to write a literature review

Summary

• Writing a literature review should be methodical. Search the literature for relevant sources, evaluate and analyse them. Before long you should find a gap in the knowledge.
• Doing a literature review demonstrates that you are aware of the current knowledge and it allows you to show how your idea contributes to your field.
• It’s all about knowing where to look and asking the right questions. This will help you to overcome the perceived enormity of the task.
• There are various ways to present your literature review and that can be down to your preference and discipline.
• Organise your literature review into three main parts: the introduction, literature and conclusions.

The literature review

The idea of a literature review is to survey the landscape for all scholarly work related and relevant to your research. It provides a general overview of the existing knowledge of a particular topic. You get to compare and critique the work of other researchers in your field. Usually, this exercise allows you to identify any gaps in knowledge. Once you’ve found these gaps, then you can begin coming up with research questions and problems that need solving. Then, you can start generating ideas for tackling a certain knowledge gap. After all, you may already have a brilliant idea, but what if someone else has done it already? The only way you can know this is if you do a literature review.

The process of writing a literature review should be systematic. First, you need to search and gather as many relevant sources from the literature as possible. Then, you need to evaluate them. With evaluating sources, you need to figure out the research question or societal problem that you are trying to address. You need to see how certain ideas and theories compare against each other. Do they agree or disagree? You can even critique these sources to point out which is more reliable and trustworthy. But do this tactfully and remain unbiased. Once you’ve read enough of the literature you will start to see missing pieces to the overall puzzle. This is the gap in knowledge. Next, you’ll need to devise the style and structure of your literature review and then you need to write it.

Why do one

Demonstrates your awareness

Typically, whenever you embark on a research endeavour, be it part of a master’s degree course or PhD, you are expected to include a literature review chapter in your dissertation/thesis. The idea is that you demonstrate your awareness of the most up-to-date knowledge in your field and show how your research will fit neatly in.

As already mentioned, you by now have an idea of the gap in knowledge in your field so you can begin brainstorming for ideas to tackle your research question or societal problem. You may stumble on an idea from reading the works of other authors or perhaps you may end up combining two or more concepts that you discover in the literature. Either way, you need to come up with a methodology for that idea. A clear plan of action involving tests or experiments. All of this presented to your readers will let them know what you have learnt, what your novel idea is and how you plan to execute that idea. Done well, this will give your readers a good reason to care about your work and understand your motivation for doing it.

It was the first thing I had to do

I spent the first six months of my PhD writing a literature review and it really was a useful exercise. The only thing I can compare the start of my PhD to is a baby learning to walk. It’s a gradual and daunting process at first. But like with a baby, eventually walking will become second nature. This all comes with time, effort and patience. I was given a bunch of journal articles by my PhD supervisor at the start.

I was also given a PhD dissertation that had a very similar theme to my research. This helped me out immensely because as much as you know your stuff it’s always helpful to be pointed in the right direction. Moreover, the PhD dissertation had a literature review chapter which was a great starting point for writing my own literature review as it pointed out all of the relevant sources that were worth reading. I strongly recommend getting hold of a recent copy of a PhD dissertation that is related to your area of research for this very reason.

Searching the literature

In the past, one would have to spend countless hours in the local library reviewing only physical sources that were available to you. Now, electronic copies of textbooks, articles, newspapers, etc. can be found through your library or the internet. Information has never been easier to access. Now, there’s so much information out there. Where do you begin? How much can you read? This is up to you. Just as important is knowing where to look and knowing the right questions to ask.

Before you begin, you need to have some idea of what your research question or societal problem is. You’re probably thinking, ‘wait, aren’t I supposed to read the literature first and then come up with a research question or a problem worth solving?’ You’ll be forgiven for thinking that. However, at the very start, your supervisor should give you an idea of where your research is likely to head and what kind of research question or problem you’ll likely tackle. As I already mentioned, my PhD supervisor gave me a bunch of useful resources at the beginning of my research. If your supervisor has not done so already, then ask them to as that’s what they are there for. Failing that, you can always look for review articles online. These are essentially literature reviews that have been published in online scientific journals.

Like a working title, your research question or societal problem is liable to change based on what you discover in the literature. Like being given directions from a trusted person, you may find that there’s an even better route to take or perhaps an even better or more interesting destination to visit. You’ll only know until you begin reading some key sources from the literature. It’s always good to be cognisant of this early on.

Keywords

When looking for relevant sources you must begin by making a list of relevant keywords related to your area of research. Here you have to be creative and imaginative. Think up words or key concepts that are involved in your research. For example, if your research involves developing a more eco-friendly and cost-effective way of recycling old car batteries your keywords could be ‘car battery recycling’, ‘car battery technology’, ‘recycling technology’, etc.

For all of my journal articles, I had to submit a list of relevant keywords to be associated with each one. This was done so that my articles would rank for their specific keywords in various search engines. So, I had to think of keywords that I thought my readers may use to search for articles just like mine. I had to get in the mind of my readers.

Now, going back to generating a list of keywords to help you search for relevant sources. If you were to write a journal article about investigating novel car battery recycling technologies, what keywords would you choose to rank for in a search engine? If you find that you’re still struggling to come up with a list of keywords, then hopefully by now your supervisor has supplied you with a few journal articles to start you off. Most journal articles will include a list of keywords on the first page. Use these to help you search the literature.

Places to look

We are spoilt with where to find information these days. The question is: where’s the best place to look? I’m going to assume you have plenty of access to the internet as this is where pretty much all of your literature search will take place.

If you study or work at a university, then you should have access to a physical library usually located on-campus. Most of these libraries have an online catalogue where you can search for all kinds of resources. Ask a member of staff at the library if you need help using the online catalogue.

I have always found Google Scholar to be very handy when it comes to searching for literature online for most disciplines.

There are also other online databases out there that you can use based on your particular discipline:

• Physics, engineering and computer science – Inspec.
• Life sciences and biomedicine – Medline.
• Humanities and social science – Project Muse.
• Economics – EconLit.

Boolean operators

I wish I used more of these during my student days. Boolean operators can be an invaluable tool for filtering through the vastness of the literature. The Boolean operators are the words ‘AND’, ‘OR’ and ‘NOT’.

So, you can include the word ‘AND’ in your search entry to find results in a search engine that will contain all your entered keywords. Using the previous keyword examples, you could enter the following into a search engine: ‘car battery recycling AND car battery technology’.

You can use ‘OR’ to perform a broader search that will retrieve search results containing either keyword but not necessarily all of them. When inputting ‘car battery recycling OR car battery technology’ into a search engine it should return results containing either keywords and in some instances both.

Using ‘NOT’ will return search results that will contain the keyword(s) preceding it and exclude items that contain keywords following it. Inputting ‘car battery recycling NOT car battery technology’ into a search engine will only find you items containing information on car battery recycling and exclude items that mention car battery technology.

Evaluating your sources

You may begin to notice that certain publications are cited in many of your sources. This is a sign that these publications are viewed as quite significant in your area of research. Get your hands on a copy of these publications and include them in your literature review. A good marker for a credible and reliable source is its number of citations. A relatively high number of citations can mean that this particular publication is quite influential. But it’s always worth checking it through to make sure it is what you think it is. After all, if it turns out that this particular publication contains many glaring errors, then it will fall on you as to why you chose to include this source in your literature review.

You’ll likely have so many sources by this point that you won’t know which to include in your literature review. A handy tip for quickly sifting through journal articles is to read the abstract. If you find that this article is relevant to your research then look over the conclusions section. If you still find that the information is relevant then this source can be included in your list of things to read through.

Now you have your reading list, you need to start evaluating your sources. When reading these sources, you need to ask yourself:

• What is the research question or societal problem being tackled?
• What are the main ideas and concepts that are being used to tackle the issue?
• Is a more traditional approach or methodology being used or is it something novel and original?
• What are the main conclusions of the source?
• Do your sources agree or disagree with each other?
• What are the main arguments that stand out to you?
• What are the strengths and weaknesses of each source?

Cite and reference

I discuss at length the importance of citing and referencing appropriately and correctly in my blog ‘How to cite and reference’. Not doing so can result in plagiarism which can land you in trouble. I recommend using a reference management system (RMS) like Endnote or Mendeley. Start building your reference library by downloading citation files associated with each source and import them into your RMS. Some citation files may contain mistakes so always double-check them for errors and spelling mistakes.

Style and structure

The style and structure of your literature review will come down to you and your discipline. You can even combine styles so long as the finished article does not confuse your readers.

Chronological

You could choose to discuss all sources chronologically. You can discuss how your area of research has changed over the years. But don’t just summarise the history of your research topic, weave the sources together to tell a story. Critique the sources and offer an objective opinion on them.

Thematic

If you notice during your survey of the literature that certain ideas and themes keep appearing then you can organise your literature review into subsections covering each theme. In each subsection, discuss and review each theme in turn. Perhaps you could cover the evolution of each theme over time and combine this style with the aforementioned chronological approach.

Theoretical

You may discover from the literature that quite a few theories, ideas and models have been developed over time in your area of research. You can review and critique each one and even look into the viability of combining two or more of them. Maybe they are wildly different and it’s not possible to do this, but you can still examine each one to see which is the most suitable for your proposed research.

Methodological

For areas of research that cover multiple disciplines, you may benefit from comparing the different methodologies commonly used in either discipline. I had to work with many individuals from different disciplines and witnessed first-hand how differently those people can think. A mathematician, physicist and chemical engineer may think and deal with the same problem in completely different ways.

Comparing the different approaches from various disciplines to see which is the most effective one for tackling your research question or societal problem can make for an interesting read. Perhaps different methods could be combined.

Write!

Your literature review is likely to be quite long especially if you’re writing one for a dissertation. So, consider breaking it down into three main parts: the introduction, literature and conclusions.

Introduction

This is where you explain to your readers the reasons behind your literature review. You can do this by reiterating your research question or societal problem based on the gap in knowledge that you have found. Then explain how this fits into the broader context of your research area.

Literature

Depending on the style that you want to adopt you can break down this section into further subsections. Here you need to give a summary of your sources. You then need to analyse and interpret them for your readers. Then you need to critique them by discussing the strengths and weaknesses of each source.

Conclusions

Here you round up the major findings from your literature review and discuss how they will influence your research moving forward.

Consider publishing your literature review

It was only until my PhD supervisor read my literature review chapter for my PhD dissertation that he suggested I publish it. The thought had never crossed my mind. Now my review article is currently my most highly-cited publication and when you’re working in academia this is a good thing.

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