[R] boxplot statistics

[Roger Bivand]

On Tue, 4 Oct 2005, Karin Lagesen wrote:

> 
> I have read and reread the boxplot and the boxplot stats page, and I
> still cannot understand how and what boxplot shows. I realize that
> this might be due to me not knowing enough statistics, but anyway...
> 
> First, how does boxplot determine the size of the box? And is the line
> inside the box the mean or the median (or something completely
> different?) And how does it determine how long out the whiskers should
> go?
> 
> Also, the boxplot.stats page talks about "hinges", what are those?  
> "The two "hinges" are versions of the first and third quartile, i.e.,
> close to 'quantile(x, c(1,3)/4)'."
> 
> Thankyou very much.

The reference on the help page is:

     Chambers, J. M., Cleveland, W. S., Kleiner, B. and Tukey, P. A.
     (1983) _Graphical Methods for Data Analysis._  Wadsworth &
     Brooks/Cole.

and a search in BIBSYS suggests that a copy is in your university library:

 author = Chambers and title word = Graphical and material type = Books

The references are there to suggest where to look for the information you 
asked for.

> 
> Karin
> 

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no