Is it better to repeat a caption or reference an identical caption?

Question

I am presenting several (11) data sets in a written communication (my dissertation). I have grouped the data separating it into several figures which fill two and a half pages, one after the other. Each figure shows the same three subplots, just with the new data set.

Is it better to include the same caption in each set of subfigures (a fifth of the page each time) or to reference the previous caption?

The first option would repeat the something like the following (this is a mock example):

Fig 6. 2x167 in 10–200 mM KCl: (a) shows the reduced intensity for the varied sample conditions with the inset showing a key region. (b) shows how the scale applied to each data as a function of the concentration. (c) shows the time dependence.

The second option would have subsequent captions that look something like the following:

Fig 7. 3x167 in 10–200 mM KCl: (a)–(c) as labeled in Fig. 6.

Edit: I was originally inclined to do the first as I am not short on space, but the fact that they are identical has made me less certain. Also, with the captions, two of the groups each fill a page, breaking up the overlapping sentence significantly. This would be somewhat less of a problem if I had more to say about the figure, but I do not need a page of text to explain the differences. I could put them all in an appendix, and only show an example (or make them smaller, as long as the labels do not get too small).

Answer 1

It depends on several factors:

• Can you expect readers to read this part of the caption only once and remember everything important for the rest of the reading? Or do you expect that readers need to constantly consult the caption to understand your figure?
• Do you expect figures to be read in order? Or is it likely that a reader will look at a later figure in the series first?
• How much information does the caption contain? This is not the same as the first point, as not all of this information needs to be important. Also, this is not exactly about length; a short caption with a lot of numbers is worse than a long caption describing straightforward concepts.
• Do you need the space used by the repeated captions?

Positive answers to the respective first questions are in favour of referencing.

But why reference at all, unless you need the space? Because redudancy, in particular in technical aspects is annoying and time-consuming for the reader. If a caption references another caption the reader still remembers, this is the quickest way of communicating it. Otherwise the reader has to read the same (usually boring) text again. Moreover, if there is an unneeded redundancy, I would expect that there is a reason for this, e.g., that you changed some details of what is described in the caption. This would usually make me frantically compare the two caption (and thus flipping back and forth).

If you have the space, I suggest a third way that takes the best of both worlds:

Fig 7. 2×167 in 10–200 mM KCl: (a)–(c) as labeled in Fig. 6, namely: (a) shows the reduced intensity for the varied sample conditions with the inset showing a key region. (b) shows how the scale applied to each data as a function of the concentration. (c) shows the time dependence.

This way, all the information is available for the reader who does not remember or has never read the earlier figure’s caption. But the reader who did, knows that the rest of the caption is redundant.

Answer 2

In a similar situation, I think I put something like "Fig. 6: Results for case X [see text]"...

Ideally, the captions should be self-contained, but in repetition, IMHO, you can skip the long text if you make it clear that is the same situation...

Answer 3

If you aren't in a bad space crunch, I would recommend putting the full caption in each one, just as if all of the other captions did not exist. That way, a person who is looking at the figure can get all of the information in one place, rather than needing to flip back and forth between a figure and the relevant caption on another page.

Answer 4

I'd place a summary caption (different in each case, explaining the differences that justify the different figures) under each of the figures, summarize in the text that "figures 1 through 25 show that..." and perhaps add a table highlighting differences. If they truly show the same (or only slightly different) situation, perhaps the best solution is to plot different curves/sets of data on one figure only (or a small set of figures, perhaps with one "general summary curve").

Answer 5

I prefer the former one (as a reader)

(a) journals are now published on-line, and the space limitation won't be a problem in the long run.

(b) fewer people read papers from the beginnings to the ends. Most of them would skim through, and they probably won't enjoying jumping through the figures just to figure out what does a line mean.