Dear Birgit, You need to think about why you have that many NA's. In case of vegetation data, it is very common to have only a few species present in a site. So how would you record the abundance of a species that is absent? NA or 0 (zero)? One could argument that it needs to be NA because you can't measure the abundance of the species that is absent. But others could argument that a missing species has by definition zero abundance. In my opinion it's best to use 0 (zero) for absent species and NA for present species but with missing information on the abundance.
HTH, Thierry ---------------------------------------------------------------------------- ir. Thierry Onkelinx Instituut voor natuur- en bosonderzoek / Research Institute for Nature and Forest Cel biometrie, methodologie en kwaliteitszorg / Section biometrics, methodology and quality assurance Gaverstraat 4 9500 Geraardsbergen Belgium tel. + 32 54/436 185 [EMAIL PROTECTED] www.inbo.be Do not put your faith in what statistics say until you have carefully considered what they do not say. ~William W. Watt A statistical analysis, properly conducted, is a delicate dissection of uncertainties, a surgery of suppositions. ~M.J.Moroney -----Oorspronkelijk bericht----- Van: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Namens Birgit Lemcke Verzonden: vrijdag 23 november 2007 16:43 Aan: R Hilfe Onderwerp: [R] PCA with NA Dear all, (Mac OS X 10.4.11, R 2.6.0) I have a quantitative dataset with a lot of Na´s in it. So many, that it is not possible to delete all rows with NA´s and also not possible, to delete all variables with NA´s. Is there a function for a principal component analysis, that can deal with so many NA´s. Thanks in advance Birgit Birgit Lemcke Institut für Systematische Botanik Zollikerstrasse 107 CH-8008 Zürich Switzerland Ph: +41 (0)44 634 8351 [EMAIL PROTECTED] ______________________________________________ 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.
