> I noticed that the boxplot function incorrectly calculates the
> location of the median line in each box. As a simple example,
> the dataset [1, 2, 3, 4] incorrectly plots the median line at 3.
I can confirm this.
> I would suggest that mlab.prctile be fixed to conform to some one
> or other of these methods, rather than adding to the proliferation of
> approaches to quantile-calculation. Is there any motivation for
> always truncating to integer (other that "it's quicker to type" :-)?
And I agree here. I also recently (before I noticed this thread) posted a bug report #3151034 
There is also documented, that the mlab.prctle function does not yield the same results as scipy.stats.scoreatpercentile. In addition to make the confusion complete matlab reports yet another result ... But I think at least matplotlib and the scipy-stats-package should agree.
Jochen Deibele, PhD candidate, Dipl.-Ing.
Department of Circulation and Medical Imaging
Norwegian University of Science and Technology (NTNU)
Phone: +47 728 28028 E-Mail: jochen.deibele@...2639...