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Abstracts are important because they give a first impression of the document that follows, letting readers decide whether to continue reading and showing them what to look for if they do. Though some abstracts only list the contents of the document, the most useful abstracts tell the reader more. An abstract should represent as much as possible of the quantitative and qualitative information in the document, and also reflect its reasoning. Typically, an informative abstract answers these questions in about 100-250 words:
- Why did you do this study or project?
- What did you do, and how?
- What did you find?
- What do your findings mean?
If the paper is about a new method or apparatus the last two questions might be changed to
- What are the advantages (of the method or apparatus)?
- How well does it work?
Here are some other points to keep in mind about abstracts:
- An abstract will nearly always be read along with the title, so do not repeat or rephrase the title. It will likely be read without the rest of the document, however, so make it complete enough to stand on its own.
- Your readers expect you to summarize your conclusions as well as your purpose, methods, and main findings. Emphasize the different points in proportion to the emphasis they receive in the body of the document.
- Do not refer in the abstract to information that is not in the document.
- Avoid using I or we, but choose active verbs instead of passive when possible (the study tested rather than it was tested by the study).
- Avoid if possible avoid trade names, acronyms, abbreviations, or symbols. You would need to explain them, and that takes too much room.
- Use key words from the document. (For published work, the abstract is “mined” for the words used to index the material—thus making it more likely someone will cite your article.)
Because the abstract is a short (short!) summary of your paper or poster, you have a limited amount of space to get your point across. Here are the essential components that should be included, and about how much space you should allow yourself for each part:
- Background (2-3 sentences): Provide just enough background to “set the scene” – the bare minimum necessary to make what follows understandable. Each sentence should narrow the focus, so go from “Cancer is a worldwide problem…” to “Liver cancer in particular causes x% mortality…” to “Protein x plays an important role in liver cancer…”.
- Question (1 sentence): What was the goal of your study? State your hypothesis or question clearly and succinctly.
- Results (4-5 sentences): This is the “meat” of the abstract, so devote most of your allotted space to this portion. I generally aim to sum up each figure or section of the paper in one sentence of the abstract. You’ll have to include some experimental detail for the results to make sense, so these sentences will often take the form of: “When the expression of protein x was knocked down by RNAi, the cells did x, suggesting that…”. Try to avoid specific values, though (percentages, concentrations, standard error, etc.), as these will bog down the reader.
- Conclusions (1-2 sentences): Sum up very quickly why your results are important by tying them back in to the issue you mentioned in the introductory sentence. You don’t want to provide any new information here, just tie it all together. It’s handy to use a stock phrase like “In conclusion…”, or “Taken together, these results show…” to finish things up neatly.
Things to keep in mind
Aside from the above pointers on what to include in your abstract, there are a few additional points that it’s worth considering:
- Word limit: Make sure that you check the journal’s guidelines for the word limit of the abstract before you get too carried away. I usually write up a draft including everything I think needs to be in the abstract, then check the word limit and add or delete material as appropriate. Don’t spend too much time tweaking the details without knowing how much space you have to work with!
- Formatting: Many journals also have specific guidelines for formatting your abstract, i.e. whether or not to include section titles. Take a quick look and see if there are any other formatting issues you need to take into consideration.
- Referencing: One quirk of scientific writing is that it’s very rare to use citations in an abstract. This is why it’s a good idea to keep your background quite vague in the abstract, so you won’t have to cite previous papers. It’s also common practice to leave something uncited in the abstract, but cite it immediately in the introduction to the paper, to make sure credit is given where credit is due.
I encourage you to spend some dedicated time writing your abstract – don’t just dash it off at the end, right before the submission deadline for that poster session! People will decide whether or not to devote their time and attention to the work you’re presenting based on the contents of that abstract. Make it easy to understand what you did, and easy for people to agree with you that your results are important and worth their attention.
What are your tips for writing killer abstracts?