I general, you should not be worrying about normality of the "tip" data, but rather the residuals of whatever multiple regression-type model you are implementing. Check those, and maybe they will be OK with a particular combination of independent variables. Bad residuals can adversely affect the likelihood of a model, so particularly check for big outliers.
Cheers, Ted Theodore Garland, Jr. Professor Department of Biology University of California, Riverside Riverside, CA 92521 Office Phone: (951) 827-3524 Wet Lab Phone: (951) 827-5724 Dry Lab Phone: (951) 827-4026 Home Phone: (951) 328-0820 Facsimile: (951) 827-4286 = Dept. office (not confidential) Email: tgarl...@ucr.edu http://www.biology.ucr.edu/people/faculty/Garland.html Experimental Evolution: Concepts, Methods, and Applications of Selection Experiments. 2009. Edited by Theodore Garland, Jr. and Michael R. Rose http://www.ucpress.edu/book.php?isbn=9780520261808 (PDFs of chapters are available from me or from the individual authors) ________________________________________ From: r-sig-phylo-boun...@r-project.org [r-sig-phylo-boun...@r-project.org] on behalf of Pascal Title [pascalti...@gmail.com] Sent: Thursday, May 10, 2012 8:46 PM To: r-sig-phylo@r-project.org Subject: [R-sig-phylo] nonparametric PGLS Hi everyone I have character data for species on a phylogeny, but simple transformations like log-transformations or square-root transformations are not proving to be sufficient to get the data to be normal. If this were a non-phylogenetic test, I would resort to something like a Spearman correlation, which is non-parametric. But with phylogenetic generalized least squares, is there any method that is nonparametric? Thanks! -Pascal Title [[alternative HTML version deleted]] _______________________________________________ R-sig-phylo mailing list R-sig-phylo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-phylo _______________________________________________ R-sig-phylo mailing list R-sig-phylo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-phylo
