Hi all,

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)

, but how do I test the interaction?

Thanks in advance,

Simon.





Dr. Simon Pickett
Research Ecologist
Land Use Department
Terrestrial Unit
British Trust for Ornithology
The Nunnery
Thetford
Norfolk
IP242PU
01842750050

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