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]] > > > > ______________________________________________ > > R-help@r-project.org mailing list > > 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@r-project.org mailing list > 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. -- %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% Dr. Gavin Simpson [t] +44 (0)20 7679 0522 ECRC, UCL Geography, [f] +44 (0)20 7679 0565 Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ UK. WC1E 6BT. [w] http://www.freshwaters.org.uk %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% ______________________________________________ R-help@r-project.org mailing list 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.
