Re: [R] Impaired boxplot functionality - mean instead of median

From: Berton Gunter <gunter.berton_at_gene.com>
Date: Fri 02 Dec 2005 - 05:53:18 EST


It's already there in EDA! Se pp 39-47.

"The business of the statistician is to catalyze the scientific learning process." - George E. P. Box    

> -----Original Message-----
> From: r-help-bounces@stat.math.ethz.ch
> [mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of
> Michael H. Prager
> Sent: Thursday, December 01, 2005 10:11 AM
> To: r-help@stat.math.ethz.ch
> Subject: Re: [R] Impaired boxplot functionality - mean
> instead of median
>
> All--
>
> Would someone kindly post the reference to Tukey's formula
> for a boxplot
> without whiskers?
>
> I am looking at his book "Exploratory Data Analysis" from 1977. The
> index includes "box-and-whisker" plot but not "boxplot." On
> page 39-40
> construction of the plot is described, including the statements: "We
> draw a long, thinnish box that stretches from hinge to hinge,
> crossing
> it with a bar at the median. Then we draw a 'whisker' from
> each end of
> the box to the corresponding extreme."
>
> MHP
>
>
> on 12/1/2005 11:57 AM P Ehlers said the following:
>
> >I'd like to add two comments to Martin's sensible response.
> >
> >1. I've seen several intro-stats textbooks that define a
> >boxplot to have whiskers to the extreme data values
> >and then define Tukey's boxplot as a "modified" boxplot.
> >I wish authors wouldn't do that.
> >
> >2. I've also seen boxplots used for sample sizes as small
> >as -- are you ready for it? -- n = 2!! (Admittedly, only in
> >plots comparing several groups.) The help page for
> >stripchart() points out that stripcharts "are a good
> >alternative to boxplots when sample sizes are small".
> >My own rule-of-thumb: n > 20 for single boxplots, n > 12
> >for multiple boxplots.

> >
> >Peter Ehlers
> >
> >Martin Maechler wrote:
> >
> >
> >
> >>Boxplots were invented by John W. Tukey and I think should be
> >>counted among the top "small but smart" achievements from the
> >>20th century. Very wisely he did *not* use mean and
> standard deviations.
> >>
> >>Even though it's possible to draw boxplots that are not boxplots
> >>(and people only recently explained how to do this with R on this
> >> mailing list), I'm arguing very strongly against this.
> >>
> >>If I see a boxplot - I'd want it to be a boxplot and not have
> >>the silly (please excuse) 10%--------90% whiskers which
> >>declare 20% of the points as outliers {in the boxplot sense}.
> >>
> >>If you want the mean +/- sd plot, do *not* misuse boxplots
> >>for them, please!
> >>
> >>Martin Maechler, ETH Zurich
> >>
> >>
> >>
> >>
> >>>>>>>"Evgeniy" == Evgeniy Kachalin <ka4alin@yandex.ru>
> >>>>>>> on Thu, 01 Dec 2005 19:04:47 +0300 writes:
> >>>>>>>
> >>>>>>>
> >> Evgeniy> Hello to all users and wizards.
> >> Evgeniy> I am regulary using 'boxplot' function or its
> analogue - 'bwplot' from
> >> Evgeniy> the 'lattice' library.
> >>
> >> [there's the lattice *package* !]
> >>
> >> Evgeniy> But they are, as far as I understand, totally
> >> Evgeniy> flawed in functionality: they miss ability to
> select what they would
> >> Evgeniy> draw 'in the middle' - median, mean. What the
> box means - standard
> >> Evgeniy> error, 90% or something else. What the
> whiskers mean - 100%, 99% or
> >> Evgeniy> something else.
> >> Evgeniy> Is there any way to realize it? Or is there
> any other good data
> >> Evgeniy> visualization function for comparing means of
> various data groups?
> >> Evgeniy> Ideally I would like to have a bit more
> customised function for doing
> >> Evgeniy> that. For example, 'boxplot(a~b,data=d,mid='mean').
> >>
> >>
> >> Evgeniy> --
> >> Evgeniy> Evgeniy, ICQ 38317310.
> >>
> >>______________________________________________
> >>R-help@stat.math.ethz.ch mailing list
> >>https://stat.ethz.ch/mailman/listinfo/r-help
> >>PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
> >>
> >>
> >
> >______________________________________________
> >R-help@stat.math.ethz.ch mailing list
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> >PLEASE do read the posting guide!
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> >
> >
>
> --
>
> Michael Prager, Ph.D.
> Population Dynamics Team, NMFS SE Fisheries Science Center
> NOAA Center for Coastal Fisheries and Habitat Research
> Beaufort, North Carolina 28516
> http://shrimp.ccfhrb.noaa.gov/~mprager/
> Opinions expressed are personal, not official. No
> government endorsement of any product is made or implied.
>
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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Dec 02 06:22:55 2005

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