On Wed, 2010-06-30 at 09:13 +0200, Stephan Kolassa
wrote:> Hi Elaine,
>
> in general, stepwise selection is a very bad idea:
>
> Whittingham, M. J.; Stephens, P. A.; Bradbury, R. B. & Freckleton, R.
P.
> Why do we still use stepwise modelling in ecology and behaviour? Journal
> of Animal Ecology, 2006, 75, 1182-1189
Another reference to consult in the same field is:
Dahlgren J.p. (2010) Alternative regression methods are not considered
in Murtaugh (2009) or by ecologists in general. Ecology Letters 13(5)
E7-E9.
which is a comment to
Murtaugh P.A. (2009) Performance of several variable-selection methods
applied to real ecological data. Ecology Letters 12(10) 1061-1068
Luckily, there are several packages available in R that implement ridge
regression or the lasso and related techniques. See for example the
Regularization and Shrinkage section in:
http://cran.r-project.org/web/views/MachineLearning.html
HTH
G
>
> HTH
> Stephan
>
>
> elaine kuo schrieb:
> > Dear list,
> >
> > I wanna select the significant variables relative to bird
distribution,
> > using stepwise method.
> > However, the result is always the best-fit model.
> >
> > Please kindly suggest if it is possible to show the selection process.
> > Thank you
> >
> > Elaine
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
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> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
>
> ______________________________________________
> R-help at r-project.org mailing list
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
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