Sub: using glmer to fit a mixed-effects model with gamma-distributed response variable
Hello, I'm currently trying to fit a mixed effects model , i.e.: > burnedmodel1.2<-glmer(gpost.f.crwn.length~lg.shigo.av+dbh+leaf.area+ bark.thick.bh+ht.any+ht.alive+(1|site/transect/plot), family=gaussian, na.action=na.omit, data=rws30.BL) If I run this code, I get the error below: Error: length(f1) == length(f2) is not TRUE In addition: Warning messages: 1: In plot:(transect:site) : numerical expression has 175 elements: only the first used 2: In plot:(transect:site) : numerical expression has 175 elements: only the first used Someone on this forum made the following suggestion, > rws30.BL$site <- factor(rws30.BL$site) > rws30.BL$transect <- interaction(rws30.BL$site, rws30.BL$transect, drop = TRUE) > rws30.BL$plot <- interaction(rws30.BL$site, rws30.BL$transect, rws30.BL$plot, drop = TRUE) Which once run allows the above code to run for a gaussian family. However, if I try to fit a gamma family model (my goal), i.e. > burnedmodel1.2<-glmer(gpost.f.crwn.length~lg.shigo.av+dbh+leaf.area+ bark.thick.bh+ht.any+ht.alive+(1|site/transect/plot), family=Gamma, na.action=na.omit, data=rws30.BL) I get: Error: no valid set of coefficients has been found: please supply starting values In addition: Warning message: In log(ifelse(y == 0, 1, y/mu)) : NaNs produced How do I determine what reasonable starting values are? And what's up with the NaNs? Thanks for taking a look. *Ben Caldwell* PhD Candidate University of California, Berkeley [[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.