[R] Impaired boxplot functionality - mean instead of median

[Berton Gunter]

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

-- Bert Gunter
Genentech Non-Clinical Statistics
South San Francisco, CA
 
"The business of the statistician is to catalyze the scientific learning
process."  - George E. P. Box
 
 

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of 
> Michael H. Prager
> Sent: Thursday, December 01, 2005 10:11 AM
> To: r-help at 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 at 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.
> >>
> >>______________________________________________
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> >>    
> >>
> >
> >______________________________________________
> >R-help at stat.math.ethz.ch mailing list
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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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