[R] strange QQ-Plot

[ripley@stats.ox.ac.uk]

On Sun, 8 Dec 2002, Fred Jopp wrote:

> i am working on a data set with EDA. That includes QQ-Plots of
> residuals vs expected normal distribution.
> What puzzles me is that the range of ordinate and abscissae is
> so different: while the theoretical quantiles range from [-2, 2]
> the sample quantiles on the ordinate do extent from [-20, 50].
> Quite obviously some kind of transformation is done.
>
> Although i intensively RTFM i could not find, what is done here.
> What exactly characterizes the range of the ordinate in QQ-Plots ?

A qqnorm plot (is that what you meant?) is of a sample against a
*standard* normal.  One expects a straight line of slope sigma and
intercept mu.

The answer to your final question is `whatever the users specifies'.
QQ plots are much more general than you seem to think.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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