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

From: Kjetil Brinchmann Halvorsen <kjetilbrinchmannhalvorsen_at_gmail.com>
Date: Fri 02 Dec 2005 - 10:28:22 EST

P Ehlers wrote:
> 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.

Woul've it make sense to have an option to replace boxes with dotplots for only those groups with number of observations lesser tahn nmin=20 (say)

Kjetil

>
> 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
> 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
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 10:33:55 2005

This archive was generated by hypermail 2.1.8 : Fri 03 Mar 2006 - 03:41:26 EST