Your literature review is the lynchpin of your paper. It puts your paper in the context of everything else that’s been done, so far, in your field. It supports your paper, while helping answer the all important question: “Why?”
Why is this paper important? What’s missing in the existing literature? Why is it important to fill that gap? How does your research help fill what’s missing?
Rules of Thumb for literature review length
Here are a couple quick rules of thumb:
- For a research paper or journal article, the literature review is generally 2 to 5 pages long.
- For a thesis or dissertation, the literature review is generally 30 to 50 pages long. The median dissertation is 177 pages long (see below).
- A quick rule of thumb is approximately 20% of the length of the entire paper.
- For example, if you’re writing a 10 page research paper, then 2 pages is about the right length.
- Likewise, for a 177 page dissertation, 20% would be 35 pages.
- These are double spaced pages.
The above said, the length can still vary by quite a bit. 30 to 50 pages is a big range.
Let’s dive a little deeper into what determines the length of a literature review.
For Research Papers: Start with the Constraints
Most papers are working within specific constraints. For example, if you’re submitting a paper to a conference, the conference will likely have publication guidelines. Those guidelines will include a length limit for the entire paper.
Likewise, if you’re planning to submit the article to a publication, the publication will likely have submission guidelines as well.
Before writing a single word, it’s a good idea to carefully read the guidelines for publication. Based on those constraints, you can decide how much of your paper to allocate to the literature review.
For Dissertations: What the Numbers Tell Us
The blogger “BeckMW” has done some fascinating research into the length of dissertations, theses, and other forms of research.
I’d encourage you to take a deeper dive into the data here and here.
The most relevant part to our discussion is this graph. This is the mead, median, and standard deviation of a PhD dissertation:
The mean comes in right around 177 pages. For a thesis, the median is closer to 70:
As stated above, the 20% rule of thumb means a ~177 page dissertation should plan to use around 35 pages, double spaced, for a literature review.
For a 75 page thesis, approximately 15 pages is a good rule of thumb.
All of this depends on the complexity and depth of your analysis. If the literature review is an integral part of your paper, it makes sense to dedicate more space to it.
Be wary of “length creep”
It’s a good idea to do as much of your research upfront as possible. Otherwise, the scope and length of the literature review and keep growing. Which means more time in cutting and editing down later on.
A good strategy is to start by gathering as many of your sources as possible, early in the writing process. Use PubMed, Science Direct, Google Scholar, etc to find related sources. Check the references & bibliography of your sources, plug them into the above tools, and read any referenced paper that has significant citations.
Start by conducting a thorough search, as opposed to adding more sources (and ideas) later on in the process.
Experimenting with Structure
There are many ways to structure a literature review. How you structure the literature review can ultimately make a big difference on the length of the review.
Instead of jumping straight into writing the literature review, it’s often a good idea to write an outline for a couple different ways to approach the review. For example, you might write an outline for how you could approach the review from a Methodological perspective, or a Thematic perspective.
Once you have a mental “preview” of what your review might look like using different structures, you’ll be able to roughly estimate what the length of the review would ultimately look like. This is especially important in cases where you have hard constraints on the length of the paper.
There are a few popular ways to structure a literature review:
Integrative
The integrative approach is one of the most flexible approaches to writing a literature review. It involves taking literature from a variety of genres - theoretical, experimental, specific studies, meta-analysis, etc. - and weaving them together in a cohesive narrative.
Thematic
The thematic approach involves extracting the common themes in the current literature, or extracting themes from data across multiple papers. This includes identifying patterns, similarities, differences, and gaps.
Chronological / Historical
Often times, the best way to present information is in order of time. This is especially true when the research question has a time element to it. For example, “How has the median opinion of vaccinations changed over time?”
In this case, reviewing literature chronologically would help illuminate changing opinions. The same can be true of methods, tools, scientific understanding, etc.
Methodological
Another way to break down a research paper is by methodology. Researchers often take very different approaches, which can lead to different results or learnings. The methodological approach tends to focus more on the methods than on the findings, though the findings still play an important role.
This approach is especially appropriate when evaluating methodologies, such as specific medical treatments or research methods.
Theoretical
Instead of comparing and contrasting methodologies, the theoretical approach outlines the various core theories in the current literature, as well as their gaps.
This method is especially important for exploring new theoretical approaches, or critiquing existing ones.
In Summary
To summarize:
- Start with the constraints. If you know how long the maximum length of the paper is, that’s a good starting point.
- As a rule of thumb, the literature review should be around 20% of the paper. Again, this is just a rule of thumb.
- Gather all your sources ahead of time. If you gather more sources at a later time, this can both change your literature review’s core arguments, as well as it’s length (this takes a lot longer!)
- Outline a couple different approaches before you start writing in earnest. This will let you both structure your thoughts better, as well choose the one that’s most appropriate for the length of your paper.
Finally, remember: no matter what approach you take with the literature review, make sure to form a strong connection between it and your own work. That’s the whole point of doing the literature review in the first place!
