[R] what does boxplot draw?

Peter Dalgaard BSA p.dalgaard at biostat.ku.dk
Sun May 11 15:31:29 CEST 2003

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


   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

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