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And make the graphics even better by labelling the lines in the chart directly instead of having to look at the legend twice* before knowing which line is for which build.

*twice: the blue line in the graphic is higher than the red one, but in the legend, it is below the red line...

Rick Wicklin

Comparing distributions has a rich history. You mention overlaying histograms (a variation of the first plot) and overlaying densities or CDFs (the second and third plots), but in some fields such as Quality Control, comparative (paneled) displays are used instead of overlays. There is also a graphical display called the spread plot that was promoted by Chambers, Tukey, and especially Cleveland in the 80s and 90s. The spread plot has fallen out of use, probably because it requires some skill to interpret it, but I saw Chambers use it in his JSM 2013 presentation last week. For a comparison of strengths and weaknesses of these approaches, see my blog post about visually comparing distributions


Rick: Am I mistaken in thinking that this cumulative spread chart is just the CDF turned sideways and upside down?

For a truly sophisticated audience, I think nothing beats the qq-plot. The problem is such a plot works only if the reader has the patience to read an essay about how to read the chart, before reading the chart!


Rclickandbuch: Good points. Elsewhere on the blog, I do mention those tips. It's not the point of this post and I didn't bother as this is not real work.

Doug Gabbard

Boxplots, anyone?


It seems to me that there's something wrong in the second line chart. Areas under the curve are not the same.


Doug: Boxplots would be great for this purpose. It will show the lower mean and lower variability clearly. I do find, though, that nontechnical people often have trouble processing a boxplot. Not sure if others have similar experience.

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