I usually use mean±SD notation for reporting values. I know that many people use mean (SD) notation and I understand why.

Right now in the document I am writing I am also reporting medians but I don't know which notation I should use for the 3 measures. Any suggestions?


2 Answers 2


Both conventions you mention are ambiguous - for example you can't tell whether the number after the $\pm$ is a standard deviation, a standard error, or the half-width of an interval. (a problem that has led to numerous questions on this site).

If you're publishing somewhere that offers precise guidelines follow those, but otherwise I suggest being explicit, for example: $``\text{median } 28.5,$ $\text{ mean } 31.2,$ $\text{ standard deviation } 3.6\!"$ -- then there's no possibility of misinterpretation.

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    $\begingroup$ +1. I usually write $``31.2 \pm 3.6\text{ (mean}\pm\text{SD)}\!"$ and hope that this is clear enough... $\endgroup$
    – amoeba
    Mar 16, 2015 at 14:38
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    $\begingroup$ @amoeba That's explicit, so it looks okay to me. I wasn't trying to hold people to any one format, just avoiding ambiguity; yours does that. $\endgroup$
    – Glen_b
    Mar 16, 2015 at 14:47
  • $\begingroup$ Well, I end up using 5.0 (5) ± 0.5 (2.5) [0 - 10] for the hypothesis variable (the numbers I show here are not the true values) and inserted a footnote explaining the format Mean (Median) ± SD (Q1-Q3) [Min - Max]. For all other variables, since they are presented in tables, it was inserted a table footnote explaining the format: Mean ± SD [Min - Max] or Median (Q1-Q3) $\endgroup$
    – yohanna
    Mar 23, 2015 at 14:55

I personally usually use Mean (Median) $\pm$ SD (IQR) [Min - Max]. That's quite maximalist, so may be a bit too much for certain purposes/readers, but is a quite logical grouping of indicators (central tendency $\pm$ dispersion, with traditional indicator first, robust alternative in parenthesis), I believe. (Minimum and maximum is of course added not because they're statistically especially important or good indicators, but because on the biomedical field it is often required for ''clinical'' purposes.)

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    $\begingroup$ I actually like this idea, but only if the order is explicitly specified in the paper so the reader knows what they're looking at $\endgroup$ Apr 30, 2015 at 18:48
  • $\begingroup$ @ssdecontrol: Of course! I usually specify it in the - say - table caption. $\endgroup$ May 1, 2015 at 18:55

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