Message-ID: <x2isshzjyx.fsf@biostat.ku.dk>
Date: 2003-05-11T13:31:29Z
From: Peter Dalgaard
Subject: what does boxplot draw?
In-Reply-To: <3710.030511@eimb.ru>
Wladimir Eremeev <wl at eimb.ru> writes:
> Dear r-help,
>
> Unfortunately I cannot find in the documentation what determines
> ranges of a 'box' in the box-and-whisker plot.
>
> It is said in "Simple R" (http://www.math.csi.cuny.edu/Statistics/R/simpleR)
> that they are 1st and 3rd Qus usually.
>
> I tried to add to boxplot lines with (quantile(x,probs=0.25)), but
> lines do not coincide with edges of boxes.
The full story is in help(boxplots.stats). It's all a bit quirky, but
faithful to the original reference by Tukey. It may be illustrative to
do something like
lapply(4:10,function(i)cbind(
bxp=boxplot.stats(1:i)$stats,
qu=quantile(1:i)))
--
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907