Updated: Apr 12, 2019
The most common downfall for a great figure is a bad figure caption. However, how to construct a figure caption is not something that is commonly taught by senior researchers or others in the scientific community. So, to help all of those researchers out there trying to make a great caption to match their amazing figure, here is a few tips:
NOTE: Many journals have specific things that need to be followed for their figure captions (length, whether they want abbreviations to be defined in the legend, etc...so ensure you check with your journal of choice).
1) Figure Title
This is the first part of your figure legend right after 'Figure X.' It should either describe what you did or tell the reader what was found. The title should be representative of the entire figure including all panels.
2) Main Body
a) What was done - Usually there is some mention of the techniques used to get the data and what organisms/cells/conditions were involved.
b) What was found - A brief description of what was found should be included. This usually includes some indication of statistical test(s) used, p-values, and n's.
All symbols and features that are not obvious in a figure need to be defined in the legend (there is no need to define things that are defined in a key within the figure). Moreover, although many journals are unclear on this, you should redefine all non-standard abbreviations within the legend. This is because each figure should be able to stand on its own and not require the reader to go back in the document to look up an abbreviation. This is not always followed, however, with some journals wanting abbreviations to be defined in the first figure and that's it. So, please read the instructions carefully for your journal.
Words of Caution
Watch your verb tense. Use the following to help:
Past tense - Typically used in the figure legend when talking about the experiments conducted.
Present Tense - Used when describing something in the current figure, or when stating something about the results in the figure.
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