Both versions of this should have worked, but you are right that the first version didn't when used with `gamm', I've fixed this for mgcv 1.6-2 (`mgcv:gam' was ok). Thanks for this.
best, Simon On Wednesday 14 April 2010 09:03, JANSEN, Ivy wrote: > Hi, > > I was reading the book on "Mixed Effects Models and Extensions in > Ecology with R" by Zuur et al. > In Section 6.2, an example is discussed where a gamm-model is fitted, > with a smoother for time, which differs for each value of ID (4 > different bird species). In earlier versions of R, the following code > was used > > BM2<-gamm(Birds~Rain+ID+ > s(Time,by=as.numeric(ID=="Stilt.Oahu"))+ > s(Time,by=as.numeric(ID=="Stilt.Maui"))+ > s(Time,by=as.numeric(ID=="Coot.Oahu"))+ > s(Time,by=as.numeric(ID=="Coot.Maui")), > correlation=corAR1(form=~Time |ID ), > weights=varIdent(form=~1|ID)) > > However, in the current version of R, this does not work anymore, and > should be changed into > > BM2<-gamm(Birds~Rain+ID+ > s(Time,by=ID), > correlation=corAR1(form=~Time |ID ), > weights=varIdent(form=~1|ID)) > > It turns out that 2 of the 4 smoothers have estimated degrees of freedom > of 1, so a linear effect would be sufficient. > Now my question is how I need to change the code in order to have a time > smoother for ID=Coot.Oahu and ID=Coot.Maui, and a linear time effect for > ID=Stilt.Oahu and ID=Stilt.Maui. With the "old" R-code, this seems > trivial, but I don't have any idea how to do it in the newest R-version > (interactions with a dummy variable do not work in gamm). > > Thanks, > Ivy > > Druk dit bericht a.u.b. niet onnodig af. > Please do not print this message unnecessarily. > > Dit bericht en eventuele bijlagen geven enkel de visie van de schrijver > weer en binden het INBO onder geen enkel beding, zolang dit bericht niet > bevestigd is door een geldig ondertekend document. The views expressed in > this message and any annex are purely those of the writer and may not be > regarded as stating an official position of INBO, as long as the message is > not confirmed by a duly signed document. > > ______________________________________________ > 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. -- > Simon Wood, Mathematical Sciences, University of Bath, Bath, BA2 7AY UK > +44 1225 386603 www.maths.bath.ac.uk/~sw283 ______________________________________________ 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.