On 24.02.2011 19:15, Greg Snow wrote:
Look at ?quantile, especially the detail section on "type" and the second
reference (and the see also section). There are many different definitions of
quantiles/quartiles and different functions use different versions.
Particularly ?boxplots points to ?boxplot.stats and that points to
Tukey's "original" ?fivenum.
Uwe Ligges
-----Original Message-----
> From: r-help-boun...@r-project.org [mailto:r-help-bounces@r-
> project.org] On Behalf Of Lewis Berman
> Sent: Thursday, February 24, 2011 8:38 AM
> To: r-help@R-project.org
> Subject: [R] Boxplot not doing what I think it should
>
> My box plot below is drawing its upper whisker all the way to the last
> point, instead of showing the point as an outlier. Am I
> misunderstanding, or is it a bug?
>
> Help(boxplot) states for the parameter "range" that "this determines
> how far the plot whiskers extend out from the box. If range is
> positive, the whiskers extend to the most extreme data point which is
> no more than range times the interquartile range from the box. A value
> of zero causes the whiskers to extend to the data extremes."
>
> To my understanding, the code below, which drew the boxplot, should
> have drawn the right-hand whisker only to 387 and shown 496 as an
> outlier point. But it didn't. Using a range of 1.3 does. Horizontal
> versus vertical does not matter.
>
> Also, the right edge of the box does not show the same 3rd Quartile as
> does "summary." Explain, please.
>
>
> > sort(t5g24times)
> [1] 111 135 201 234 283 283 284 285 300 370 387 496
> > summary(t5g24times)
> Min. 1st Qu. Median Mean 3rd Qu. Max.
> 111.0 225.8 283.5 280.8 317.5 496.0
> > iqr <- 317.5 - 225.8
> > iqr
> [1] 91.7
> > 317.5 + 1.5 * iqr
> [1] 455.05
> > pdf()
> > boxplot(c(t5g24times), horizontal=1, range=1.5)
>
>
> R version info:
> platform x86_64-apple-darwin9.8.0
> arch x86_64
> os darwin9.8.0
> system x86_64, darwin9.8.0
> status
> major 2
> minor 12.0
> year 2010
> month 10
> day 15
> svn rev 53317
> language R
> version.string R version 2.12.0 (2010-10-15)
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