Finding research gaps is vital: not only do gaps spur new areas of research and advance knowledge, but they are opportunities for academic growth and success. For example, articles in the biomedical field that fill gaps are cited more heavily and are 61% more likely to be published in high-impact journals.

However, finding research gaps isn’t always easy. It can be time-consuming to sift through the existing literature on a subject, particularly in an entirely new domain. Improving this process is one our goals at Litmaps, which is why we built Discover. Once you’re properly set up it takes just a few minutes to start discovering new papers, and potential research gaps.

Below we go through a two general workflows for finding gaps in literature reviews. There are two ways the following technique can be applied: 1. On your own literature review, and 2. On an existing literature review.

First – what is a research gap?

The research gap refers to any yet unexplored or unresolved area of scientific enquiry. Although the number of gaps in research are practically infinite, finding research gaps efficiently is a challenge. Whether or not you've already complied a library of existing literature, finding research gaps is time-consuming work. Certain methods and automated tools can make finding gaps in your research easier by quickly revealing papers you haven't yet explored.

There are various methods to identify potential gaps in research. Sifting through papers, understanding the current landscape of a field and navigating the literature are all valid techniques. However, these traditional methods tend to be time-consuming, taking hours or even days to complete.

Using Litmaps Discover to find research gaps

In both of the workflows below, we use Discover to quickly find related papers. Discover is a method for searching across the references and citations of a group of articles. It'll recommend the most highly-shared connections to help identify gaps when searching across the references of a literature review.

Method 1: Searching your own literature review for gaps

This is a great way to sense-check your own literature review findings. Finding gaps in your literature coverage helps ensure your literature review is high quality. The gaps you find can also prompt you to expand and/or change the scope of your literature review.

1. Prepare your literature library

The easiest way to get started is by uploading your existing library into Litmaps. If you're already using a reference manager tool like Zotero, Mendeley or EndNote, you'll be able to export the relevant references to a "BibTeX" file. See this guide for how to do this.

If you don't have a research library set up yet, don't worry. Our Seed tool will help you to quickly create a new collection of articles based on a single one.

2. Start a new search

We're going to use the Litmaps Discover tool to try to find literature gaps.

Go to Discover and start a New Search. If you've exported a BibTeX from your reference manager click “Import from Reference Manager” and upload your BibTeX file. Otherwise, use an existing Litmaps collection by clicking "Add from Your Library" and selecting the collection you'd like to use.

When your articles are loaded, either press the >> Quick Start button, or click Next: Configure Inputs, and then Run Search.

Upload existing library to Litmaps by going to Discover tool and starting a New Search, and pressing “Import from Reference Manager”. Or, click “Add from Your Library” to use a Litmaps collection.

3. Discover unfound articles

Litmaps has searched over the citations and references of all the articles from your library, and has returned suggestions. These suggestions are displayed in the outer circle of the visual display: they've been found to be the most connected to your library through their citations and/or references.

Visualization provided by Litmaps Discover, with the input articles in the center, represented as dots. Outer ring with different markers, denoting suggested papers. Dots are connected by lines where papers reference one another.

From here you should review the suggested articles in the outer circle. By going through them, you can often unearth gaps in your research:

You'll want to look for articles you haven't seen before, but seem relevant to your topic. They should probably be covered by your literature review!
Also keep your eye out for articles which are adjacent to your literature review topic. They might not be included in your final review, but it's good practice to have an understanding of the edges of your topic – and be able to reason about why they're not included in your findings.

If you're using Litmaps Pro, you can also try Co-authorship Search as a secondary search algorithm. Plus, Pro also lets you filter by date and keyword to quickly help refine your search to be exactly what you're looking for.

4. Save new papers to your library

In just a couple of minutes, you've sifted through hundreds of references in your literature library and identified the most relevant papers.

Save these new articles to your collection by hitting the plus alongside an article's title. This way, when you click "Finish" to end the search, you're able to export a new BibteX file.

Export Litmaps collection by clicking “Finish” then “Export”

Finally, your newly-generated BibTeX file can be imported back into your reference manager.

Method 2: Searching an existing literature review for gaps

You can assess a literature review's comprehensiveness by seeing if it missed any key papers. Finding gaps in existing literature reviews can help find underserved branches of research that might be promising leads to an impactful topic.

For this example, we're going to be searching a 2007 literature review on Shilajit, a consumable natural resin with therapeutic applications.

1. Get references from the literature review

There are a few ways to extract the references for the review paper you want to investigate. Below is a demonstration of doing this within Litmaps, but check out our full guide for a more detailed explanation, and more ways of doing this.

Create a new collection
Click on "add articles", and search for your review paper. In this example, I've used the article's DOI to quickly find it.
Rather than adding this article to our collection, we want to add its references:
Go to the References tab
Select All, then click the "Add to..." button, and choose the collection you created.
The review's references are now inside your collection – you can close the search modal.

2. Use Discover to find missing papers

Next, we'll explore the library using Discover:

Go to Discover, and create a New Search
Add the review article's references – we'll use the Add from Your Library to add all articles from the collection we created earlier.
Start the search

3. Analyze the results

Discover shows suggested papers in the outer ring: they've been found to be the most connected to the references of the Shilajit review paper.

Since the articles you've searched across represent all of the references in the literature review, any articles in the outer ring can be considered “missing” from the literature review. In this case, we are interested in papers published before the date of this paper's publication (2007). These represent relevant and highly cited papers that the original literature review did not review.

In this Shilajit example, Discover identified four papers published before 2007! One of these is a highly-ranked 2002 review paper that we'd expect the 2007 paper to reference. However, the 2002 paper referred to Shilajit using another name, "Mumie". This may explain why the 2007 paper authors didn't discover and reference it at the time.

4. Search deeper using Pro

We'll set the maximum date filter to 2007 – this is the year of publication of the literature review we're focusing on. The search will now quickly reveal the most relevant papers up to that date – the research our review paper authors would have had access to.

We also enable 2º search depth, making Litmaps sift through a much broader range of articles to minimise the chance that we miss something.

Filter on date and depth of search using Litmaps Pro by selecting them as filter in the configuration of the Discover

Alternatively, we can set the filter to only see papers published after 2007. This is useful if you’re searching for new advances in research since a given paper was published – we'll write more on this topic in future, but for now we'd encourage you to experiment with what results this

5. Add missing papers to your library

Hopefully this process has led you to find some articles that the original review article missed – potentially providing new research avenues for you to investigate.

If you'd like to save some of the results you've found, simply by hit the "plus" next to an article's title. When you click Finish to end the search, you'll be able to export these articles to a BibTeX file for importing into your reference manager, or you can save them to a new collection within Litmaps for further discovery.