This post is the part of a series on how to write a paper. The first was on abstracts and the second on introductions.
The section that often follows the introduction is the related work section. The related work section may also be called a literature review. The point of the section is to highlight work done by others that somehow ties in with your own work. It may be work that you’re basing your work off of, or work that shows others attempts to solve the same problem.
There are a couple of schools of thought when it comes to writing the related work section. The first school of thought is to mention absolutely everyone and every paper that may be even remotely related to the topic at hand. Personally, I don’t like this method as it usually ends up being a long section with at most one sentence on each paper since there’s no room to give any actual amount of detail. It is also one of the reasons you may find a 4 page paper that is actually 3 pages of writing and 1 page of references.
The second is to pick and choose the most important papers and to only talk about them. This method allows the author to give about a paragraph or so of space for each paper and actually give details about what the paper is about. A paragraph of space is actually adequate to explain the contributions of the work and how it relates to your own work.
That’s the other important part of the related work. If you’re going to mention a paper, it needs to have some concrete relation to the work you’re doing. You should be able to (easily) defend each paper as to why you chose it and why it’s important. Some papers will be easy to defend – these are the papers that present work you’re building upon or papers that are about other solutions to the problem you’re working on. Others are more difficult. If it’s difficult to defend, then ask yourself why you’re including the paper and if it’s really necessary.
A few suggestions to make writing your related work section easier:
- Every time you read a paper, write a short summary of the paper and highlight an important sections. This way you can read your own recap of the paper to decide if it’s applicable instead of relying on the abstract.
- Use the reference section of the papers you read to search for other papers to read. If paper a is closely related to your topic, then likely the papers they reference are papers that are also closely related to your topic and you should read them.
- Look through the history of papers published at the journal/conference you’re submitting too. It’s likely you can find papers related to your topic.
- When writing a paragraph on a paper, make sure you can answer the question “how does this relates to my work?” If you can’t, consider not including it.
A Formula for Academic Papers: Related Work
The Related Work section of an academic paper is often the section that graduate students like writing the least. But it is also one of the most important sections to nail as the paper heads out for review. The Related Work section serves many purposes, several of which relate directly to reviewing:
- The person handling the submission will use the referenced papers to identify good reviewers,
- Reviewers will look at the references to confirm that the submission cites the appropriate work,
- Everyone will use the section to understand the paper's contributions given the state of existing research, and
- Future researchers will look to the Related Work section to identify other papers they should read.
When placing your research in the context of the existing literature, there is no need to show that prior work is all wrong to show that your paper makes a contribution. In fact, doing so is likely place reviewers and readers who have written relevant content in a combative frame of mind as they read. But these are the people you most want to listen to what you have to say! So rather than focusing on why your work is better than what has already been done, show how it builds on existing knowledge to provide additional insight. Write your Related Work section as if you were telling the cited authors why they should care about the work that you present. After all, they are the people who will probably be reviewing your paper.
Papers do not need to exist in a vacuum to be interesting, and the typical contribution that can be made in ten pages is relatively limited. While you should aim to change the world with your body of research, you are unlikely to do so within a single paper. Avoid over stating your contributions. Be particularly wary of declaring that your paper is the "first paper that we are aware of" in an area. While I know it is tempting to do so (and I am even guilty of doing it myself), statements like this usually trigger an intense related work search when I see them as I review. It should concern you if you believe nobody else has looked at an analogous problem to yours. Chances are very high that there is something similar out there that your work can draw from.
Conversely, do not freak out if you happen to come across related work during your literature search that seems to address the exact same problem that you are studying. In an ideal world you would identify all relevant work prior to starting your own research so that it can inform your approach, but in the real world that doesn't always happen. You may have holes in your initial lit review, or related work may be published after you begin a study. Surprisingly, however, this is generally a good thing. It means that other people are excited and interested in your topic, and it provides you with a fresh way of looking at things. There is a large space to study surrounding any problem, and your work probably makes a contribution. The challenge is just to figure out what that is and how to communicate it clearly to your readers.
Because reviewers will be drawn in part from the papers you cite, cite papers written by people you would like reviewing your work. Reviewers are likely to look at your citation list to ensure completeness -- and, sometimes, to ensure that papers they have written are cited. To avoid bruised egos, do not leave significant holes and try to include papers by a variety of different authors.
Include citations to your own papers when relevant, even if the paper you are writing is being submitted anonymously. There is no need to anonymize these citations. Instead, cite your papers the same way you would cite any other paper, in the third person. For example, in a paper on cross-session search I write, "Teevan et al.  showed, via query log analysis, that nearly 40% of queries were attempts to re-find previously encountered results." But while it is fine to cite your own work, be wary of over-citing yourself. Too many papers by an unexpected person typically signals that that person is an author, and generally looks bad.
A typical Related Work section follows a basic structure:
- It starts with few sentence overview of the general space, and
- A preview of areas that are particularly relevant and will be discussed in detail.
- The body consists of several paragraphs, each discussing a different relevant thread of research.
- The section ends with a paragraph summary of the paper's contributions over existing research.
In the body of the Related Work section, do not just list paragraphs that each summarize a single related paper. Summaries can be a useful way for you to build a picture for yourself of existing related work. But in the Related Work section, you should help your reader get the lay of the land by grouping and organizing the existing research. Start each paragraph with a sentence describing why the papers discussed in that paragraph are related, citing all of the papers to which the criteria applies. Then write a sentence or two about several of the most relevant papers from the group, highlighting the approach used and relevant findings. End the paragraph with a sentence explaining how the work in your paper contributes something new in light of these papers.
An example of this basic structure for a paragraph in the body of a Related Work section can be found in A Crowd-Powered Socially Embedded Search Engine:
- Overview of the papers in this paragraph:SNS question asking has been studied in many contexts, including on Facebook (Lampe et al., 2012;Morris et al., 2010;Panovich et al., 2012;Teevan et al., 2011), on Twitter (Efron and Winget, 2010;Java et al., 2007;Li et al., 2011;Paul et al., 2011), in the enterprise (Thom et al., 2011), and across cultures (Yang et al., 2011;Liu & Jansen, 2013).
- Sentences about relevant papers:
- Morris et al. (2010) found most questions posted to social network sites are subjective, seeking recommendations and opinions.
- Paul et al. (2011) showed many are also rhetorical, with the asker expecting social answers rather than informative ones.
- The prevalence of subjective and rhetorical questions on social network sites has been a challenge for socially embedded search engines like SearchBuddies (Hecht et al., 2012), a Facebook agent that algorithmically suggests URLs in response to questions.
- How this paper contributes: Our crowd-powered system handles these nuanced scenarios because people are kept in the loop.
End the Related Work section with a paragraph that summarizes what is know given existing literature, and highlight why the work to be presented in your paper offers a valuable contribution beyond this. An example can be found in Understanding How the Projection of Availability State Impacts the Reception of Incoming Communication:
In summary, the work presented in this paper builds on previous research to explore how availability information relates to people’s communication decisions. While earlier work focused on how availability information impacts the people initiating communication, we focus on its impact on the decisions of the recipient. Further, we are able to study this behavior at a much larger scale than previously possible by looking at the users of a popular enterprise communication system that infers its users’ availability.
Even though the Related Work section is very important to the overall paper, it should not be too long. It a ten page paper, a good rule of thumb is that you should be done with the paper's set-up (including the Introduction and Related Work sections) and on to the meat of the paper by the start of the third page. A good target length for a Related Work section in standard ACM format is one to two columns. To keep the section short, avoid subsections unless really necessary.
The actual list of references at the end of the paper should also be compact. I generally aim to fit the Conclusion and reference list entirely within a single final page. One way to do this is to target a reasonable number of references. I've averaged 31 references across all 10 page papers I've written since 2010. While you should not shrink the font size of your reference list, there are tricks you can play to minimize the amount of space each individual reference takes. For example, you can refer to common, well known outlets by their acronym. Do not, however, be sloppy with how you refer to papers. This can offend the paper authors and make it hard for readers to find the associated papers. Include correct, consistent details for each. Be sure to list references in alphabetical order to make it easy for the reader to scan to see if a paper is cited, since this is a task your reviewers are likely to do several times while reviewing.
Some communities place the Related Work section at the beginning of a paper, while others place it at the end. When writing a paper you should follow the norms of the community where you are publishing. However, if there is a choice about placement I recommend putting the section at the beginning. When I read papers that do not cover related work until after the main content, I find I spend much of my time reading wondering how what is being presented fits into the bigger picture.
Hopefully this post has convinced you to be thoughtful with how you place the research papers you write in context. The Related Work section is an extremely important part of the paper, and the resulting citation graph helps define the structure of the field. As a bonus, here are links to a few papers we have written that take advantage of the citation graph to make it easier to explore related work:
This post is part of a series of posts about the formula for academic papers. The components being discussed are: