On Wed, 2010-07-21 at 16:17 +0100, Karen Moore wrote: > Hi, > > I've an issue adding an interaction to a GAMM: > > My model was of form: > > gamm1 <- gamm(TOTSR ~ fROT + s(PH) + s(LOI) + s(ASP) + s(SQRT_ELEV) + CANCOV > + s(SQRT_TOTCWD) + s(WELLF) + s(WELLN) + s(OLDWDLD) + s(DISTWOOD) + > s(Annprec) + s(OLDWDLD:DISTWOOD) + (1|fSITE), family = poisson, data = > BIOFOR2) > > with interaction of s(OLDWDLD:DISTWOOD). > > However I got this error message below but don't know what it means? (my > data is composed of info for 150 plots)
An interaction is formed in a GAMM using a smoother in two or more dimensions, such as s(OLDWDLD, DISTWOOD) or te(OLDWDLD, DISTWOOD), the latter allows for different basis function within the two smoothers and for different inherent scales for the two variables. IIRC the latter allows you to produce strictly nested models for likelihood ratio testing: te(OLDWDLD) + te(DISTWOOD) is nested within te(OLDWDLD, DISTWOOD) HTH G > > #I Warning messages: > #2: In OLDWDLD:DISTWOOD : > # numerical expression has 150 elements: only the first used > #3: In OLDWDLD:DISTWOOD : > # numerical expression has 150 elements: only the first used > > Can anyone offer advice on how to include this interaction in GAMM model? > Thanks > > Karen Moore > > [[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. -- %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% 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.
