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 <[EMAIL PROTECTED]>
>>>>>>> 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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