On Tue, Mar 10, 2009 at 10:15 AM, Simon Pickett <simon.pick...@bto.org> wrote:
> This is partly a statistical question as well as a question about R, but I am > stumped! > I have count data from various sites across years. (Not all of the sites in > the study appear in all years). Each site has its own habitat score "habitat" > that remains constant across all years. > I want to know if counts declined faster on sites with high "habitat" scores. > I can construct a model that tests for the effect of habitat as a main > effect, controlling for year > model1<-lmer(count~habitat+yr+(1|site), family=quasibinomial,data=m) > model2<-lmer(count~yr+(1|site), family=quasibinomial,data=m) > anova(model1,model2) I'm curious as to why you use the quasibinomial family for count data. When you say "count data" do you mean just presence/absence or an actual count of the number present? Generally the binomial and quasibinomial families are used when you have a binary response, and the poisson or quasipoisson family are used for responses that are counts. ______________________________________________ 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.
