RE: [S] Pie diagrams anyone?

Peter Bouman (pbouman@sachs.com)
Fri, 13 Nov 1998 07:39:15 -0600


Thanks for this mention of Cleveland, who I think has done some of the best
work on quantifying problems with
pie charts.

In general, Cleveland documents that the "visual tasks" involved in decoding
the information presented in pie chart format are more
difficult and less accurate than those involved in reading, say, a dot
chart. For example, the eye just isn't as good at comparing
information encoded in angles (pie charts) as in distances along a common
scale (dot charts).

Many of us also work in areas where data points have associated
uncertainties and confidence intervals, which dot charts (e.g.) can present,
but pie charts can't.

More generally, why use a presentation format which demonstrably distorts or
hides subtle data differences, and has to be supplemented, by
Roosen's own admission, by numbers next to the pie slices? This seems to
violate the spirit of good graphical presentation of data, which
should invite the eye to make valid data comparisons on its own.

I suppose I write this only because I have seen so many poor graphical
presentations of data which often acted to obscure the very point
they were trying to make-inexcusable because there are so many good authors
in the field (Cleveland, Tufte, Tukey, et. al.) who have publicized good
practices

> -----Original Message-----
> From: Gunter, Bert [SMTP:bert_gunter@merck.com]
> Sent: Friday, November 13, 1998 7:14 AM
> To: 's-news'
> Subject: RE: [S] Pie diagrams anyone?
>
> To Messrs Venables, Roosen and others:
>
> Re: Pie Charts (and associated graphical quandaries)
>
> As this will probably "explode" into a juicy discussion, let me bite off a
> small slice early. For those who may wish some more background on these
> graphical issues -- and they HAVE been seriously considered -- two
> references:
>
> Howard Wainer's Book:VISUAL REVELATIONS: GRAPHICAL TALES OF FATE AND
> DECEPTION FROM NAPOLEON BONAPARTE TO ROSS PEROT (1997, New York:
> Copernicus)
> is a readable discussion built around many delightful examples. Wainer
> even
> has a kind of pie chart on steroids that he proposes (based on Florence
> Nightingale's original version. Yes, that is THE Florence Nightingale of
> nursing fame!). See my review of the book in the February, 98 AMERICAN
> STATISTICIAN for a quick overview of contents.
>
> A somewhat more statistical but still very readable exposition of
> graphical
> displays can be found in Bill CLeveland's, THE ELEMENTS OF GRAPHING DATA (
> 1994, New Jersey: Hobart Press. books@hobart.com), in particular, pp.
> 262-269 on the graphical perception of "Pop Charts."
>
> Enjoy!
>
>
> Bert Gunter
> Biometrics Research RY 70-38
> Merck & Company
> P.O. Box 2000
> Rahway, NJ 07065-0900
> Phone: (732) 594-7765 Fax: (732) 594-1565
>
> "The business of the statistician is to catalyze the scientific learning
> process." -- George E.P. Box
>
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