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Conducting a literature review

Posted 8/9/2022

Reviewing academic literature is necessary, but mysterious and inefficient for most scholars. There is an endless supply of papers, and it’s easy to acquire mountains of PDF files and anxiety while achieving little else. Establishing the goal of your review, and some procedures to make progress, will help shrink that mountain.

It’s hard to read papers without a goal, so start by formulating a few specific questions to answer. If I am studying future wildfire risk, my questions might include “how will climate change impact wildfires in the future?” and “what numerical techniques have analysts used to quantify wildfire impacts?” As I developed my research approach, I would read to identify similar methods and how my work advances those prior efforts. Questions will help you focus on the pertinent parts of papers, skip past irrelevant documents, and prepare you to explain how your work advances the field.

Use Google Scholar to search for papers on particular topics, and to find other documents that cite a specific paper. Consensus reports and review papers can provide broad overviews of a field, and can provide citations for studies of specific topics. Recent papers are also useful because they may cite related prior work. You can try to gauge the importance of a paper by how often it is cited, but you’ll need to evaluate whether it is important for your questions or some other topic. Women and minorities tend to be under-cited, so be careful to check for work from these groups of authors too. Another tool for finding related papers is www.connectedpapers.com. When you find authors active in your topic area, checking their web pages can provide pointers to other relevant work or context.

Once you’ve found a relevant paper, read it with specific questions in mind. Use the questions you posed during your search, and also consider the following detailed questions: How do the paper’s methods relate to yours? Do the authors comment on why they chose their methods? If they used a similar approach to yours, does this help justify your choice? If their approach differs, can you explain why your proposal is advantageous? Does the paper have gaps that you can fill? Or does their discussion point to any risks with your ideas?

Don’t read papers from beginning to end! Start by skimming the abstract, introduction, and conclusions to find clues about your questions. If they make an interesting claim, then go looking for details. If they cite prior work that might be relevant, note it to look at later. Otherwise, move on. Especially at the beginning, evaluating many papers for specific questions is more important than diving deep into a few papers.

Be skeptical. Papers are always not forthcoming with their limitations. If a result seems too good to be true, it may be. Don’t grant the most worth to the paper that makes the boldest claims. And don’t assume that the authors were all-knowing when they chose their methods.

While reading, a useful side task is to note your favorite papers. Some writing shines because of its clear structure or easy-to-read prose. Examples of good organization, language, or figures are invaluable when it comes time to write.

You’ll need a tracking system as your paper collection grows. A citation manager tool is essential because of its ability to search and add notes to your data, and later insert citations into papers. I like Zotero because it is free, open-source, and integrates with my other tools. It quickly imports data from Google Scholar or journal web pages. It also works with Latex (using Better BibTeX) to easily insert citations and references to my papers.

Beyond saving files in a reference manager, build a notes template listing your questions that you can fill in once for each paper. If your notes aren’t extensive, consider using a spreadsheet with one row per reference and one column per question—this lets you quickly sort or scroll to find papers addressing a particular question.

For the most relevant papers, outline your important topics, adding each reference followed by bullet points describing its contributions. Later, you can take relevant parts of the outline, rearrange them, and polish the text for use in a paper. It’s hard to start this outline on day one, if you haven’t yet identified your critical ideas. But get started early. If you read a huge pile of papers and then wait a few months to write your literature review, you’ll struggle to re-find key references and ideas.

Your last important decision is when to stop. Pause when you run out of relevant papers to study, but don’t consider the work finished. Show your outline to people who can give you feedback (certainly your advisor, and maybe other experts you’ve spoken with), and ask them if they’re aware of other relevant documents. Set some alerts on Google Scholar for new publications with particular keywords or from particular authors. That way, you’ll learn quickly about other new developments. This is particularly important if you plan to work on the topic for several more years. You’ll also find it useful to return to some previous papers as your work progresses and you better understand some related ideas.

The through-line of these ideas is to not just passively accumulate PDF files. Consider yourself a detective, collecting evidence to support your case that your research adds to prior work. With this process in place, you can discard extraneous information while organizing your evidence for later use.