[BioC] M vs A plot

Wolfgang Huber w.huber at dkfz-heidelberg.de
Tue Feb 10 15:56:20 MET 2004

Richard Friedman wrote:
> Dear Wolfgang,
>     I thought that span was the fraction of points used in the smoothing 
> and had a theoretical maximum of 1. I also thought that it was not a 
> good idea to use all the points in the smoothing, lest the more extreme 
> points dominate.   

Hi Richard,

See the help page for "loess", section "Details". span>1 is quite legal
and different from span=1. For a good explanation of local regression,
have a look at the book by Clive/Catherine Loader.

(And if you think that bandwidth choice in local regression is quite 
confusing, you're at a point where I've been, too ...)

Best wishes

Wolfgang Huber
Division of Molecular Genome Analysis
German Cancer Research Center
Heidelberg, Germany
Phone: +49 6221 424709
Fax:   +49 6221 42524709
Http:  www.dkfz.de/abt0840/whuber

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