Box & whisker plots with skewed distributions?


I'm just starting to use box & whisker plots
and have a (possibly very naive) question
about using them with skewed distributions.

The box represents skew in the middle of the
distribution nicely by showing the quartile
locations q1, q2, and q3. But the whisker
lengths are defined in terms of IQR=q3-q1, so
the whiskers are the same length for both tails.
This means that the skew in the tails (i.e.
below q1 or above q3) is not represented,
as far as I can see.

I wonder why the same value of IQR is used
to calculate the whiskers at both ends of the distribution.
Instead, I'd think the whisker should be longer on the side
with the longer tail. It would be easy enough to
define the whisker lengths for the two tails
separately, for example in terms of 2*(q2-q1)
and 2*(q3-q2). I'm just wondering why that
isn't routinely done. Have I overlooked
something obvious?

Thanks for your comments,

(By the way, with the distributions I am examining,
it would be very unhelpful to transform the scores
to eliminate the skew, since the skew itself is part
of what's interesting about the dataset.)
.

Relevant Pages

  • Re: Box & whisker plots with skewed distributions?
    ... about using them with skewed distributions. ... This means that the skew in the tails (i.e. ... I'd think the whisker should be longer on the side ... "Extreme" outliers, or those which lie more than three times the IQR to the left and right from the first and third quartiles respectively, are indicated by the presence of an open dot. ...
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  • Re: Box & whisker plots with skewed distributions?
    ... I'm just starting to use box & whisker plots ... This means that the skew in the tails (i.e. ... to calculate the whiskers at both ends of the distribution. ...
    (sci.stat.edu)
  • Re: Box & whisker plots with skewed distributions?
    ... So if there is much skewness, ... The pre-truncation whisker length depends ... whisker truncation itself depends only on the ... with lots of distributions, though. ...
    (sci.stat.edu)
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