Dear Rodolfo, It's apparently the case that at least one of the columns of the model matrix for your model is perfectly collinear with others.
There's not nearly enough information here to figure out exactly what the problem is, and the information that you provided certainly falls short of allowing me or anyone else to reproduce your problem and diagnose it properly. It's not even clear from your message exactly what the structure of the model is, although localizacao is apparently a factor with 3 levels. If you look at the summary() output for your model or just print it, you should at least see which coefficients are aliased, and that might help you understand what went wrong. I hope this helps, John ------------------------------------------------------- John Fox, Professor McMaster University Hamilton, Ontario, Canada http://socserv.mcmaster.ca/jfox/ > -----Original Message----- > From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of Rodolfo > Pelinson > Sent: March-27-15 3:07 PM > To: r-help@r-project.org > Subject: [R] vif in package car: there are aliased coefficients in the model > > Hello. I'm trying to use the function vif from package car in a lm. However it > returns the following error: > "Error in vif.default(lm(MDescores.sitescores ~ hidroperiodo + localizacao > + : there are aliased coefficients in the model" > > When I exclude any predictor from the model, it returns this warning > message: > "Warning message: In cov2cor(v) : diag(.) had 0 or NA entries; non-finite > result is doubtful" > > When I exclude any other predictor from the model vif finally works. I can't > figure it out whats the problem. This are the results that R returns > me: > > > vif(lm(MDescores.sitescores ~ hidroperiodo + localizacao + area + > profundidade + NTVM + NTVI + PCs...c.1.., data = MDVIF)) Error in > vif.default(lm(MDescores.sitescores ~ hidroperiodo + localizacao + > : there are aliased coefficients in the model > > > vif(lm(MDescores.sitescores ~ localizacao + area + profundidade + NTVM > > + > NTVI + PCs...c.1.., data = MDVIF)) > GVIF Df GVIF^(1/(2*Df)) > localizacao NaN 2 NaN > area NaN 1 NaN > profundidade NaN 1 NaN > NTVM NaN 1 NaN > NTVI NaN 1 NaN > PCs...c.1.. NaN 1 NaN > Warning message: > In cov2cor(v) : diag(.) had 0 or NA entries; non-finite result is doubtful > > Thanks. > -- > Rodolfo Mei Pelinson. > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. --- This email has been checked for viruses by Avast antivirus software. http://www.avast.com ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
