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What is the accepted norm for labeling axes in plots/graphs? Is it best to use the variable, spell our the variable, or a combination of both? For example, to label a time axis, we could write: t (s) or Time (s) or Time, t (s).

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closed as too broad by fileunderwater, The Hiary, EnergyNumbers, Arno, David Richerby Mar 21 at 0:18

There are either too many possible answers, or good answers would be too long for this format. Please add details to narrow the answer set or to isolate an issue that can be answered in a few paragraphs.If this question can be reworded to fit the rules in the help center, please edit the question.

This differs widely between fields, journals and reserachers, so your Q is to broad and partly opinion based. –  fileunderwater Mar 20 at 14:29
My intention was to determine if there were any sources suggesting a specific format. Do you know of any books, or journals that explicitly address this? I have browsed many journal requirements, but haven't found any. –  William Mar 20 at 14:31
Specific journals have their own detailed style guides. The example without units is certainly incorrect. Often you'll be plotting something that has no precise English description, so you have to use a symbol, even if you would otherwise have preferred to use words. –  Ben Crowell Mar 20 at 15:39
This question appears to be off-topic because it isn't close to any of the topics listed in the Help Center. –  David Richerby Mar 21 at 0:18

3 Answers 3

Good practise is to make sure the graph is understandable even when taken out of its context (the paper). Hence spelling out the label helps to avoid misunderstandings. There is, however, nothing formally wrong with the other forms you mention although the label including both variable and variable abbreviation is not common in my field. On the other hand, it serves to couple the variable name with its abbreviation so it has its merits.

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I am very particular about figures in my papers, as when I skim a paper the first thing I do after reading the abstract is look at the figures to determine whether the results are interesting or not, and on that basis whether to read the paper in more detail. Hence I always make sure the data is clearly presented through an appropriate use of symbols, colours and typeface, as well as a detailed stand alone caption describing what the data is and what it shows. As part of this I always label the axes in the form "quantity (unit)". In my opinion a variable name 't' is insufficiently descriptive to make figures stand alone, and so doesn't communicate to the casual reader what the figure shows. Units are of course essential, and in the case of dimensionless quantities I usually include the variable name as the unit, eg t/t0.

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There is nothing technically incorrect about any of those forms. In journal submissions, there will be typesetters to check that your figures adhere to their style guidelines.

In general:

The name of the quantity (e.g. time) and its units (e.g. s) are needed for clarity. It is generally better to add some concise descriptor to the quantity (e.g. Is it reaction time? geological time? etc.)

Preferences for how the units are displayed are somewhat subjective as well. An alternative format is using / as a separator (e.g. Time / s), though I personally think this format lends itself to confusion with derived quantities that contain division (e.g. Dimensionless Time, t/tc, as another user mentioned, will also have a /)

Adding the variable name (e.g. t) is often redundant in formal publications, unless equations figure extensively into the written portion and/or the naming is non-obvious or unconventional (say you used τ). Italicization will often be used to improve clarity.

Above all, consistency is critical. Choose a format, and use it for all graphs in the same manuscript. Doing otherwise just appears sloppy.

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The only thing I dislike about spelling out variable names, is the length, e.g., I could write Q* or Dimensionless Volumetric Energy. The latter can require a larger figure if the y-axis is too short to contain the word, while the former certainly doesn't have this problem. –  William Mar 21 at 21:09

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