[R-sig-eco] LRT tests in lmer

[Rob Knell]

Hello all

I apologise for asking what is probably a stupid question, but I've been going round and round in circles for a while now trying to work this out. I'm fitting a model to some data that unfortunately require a GLMM: repeated measures data with binomial errors. I'm a long way out of my comfort zone with this sort of analysis but fortunately the sample size is nice and big and the effects seem pretty clear. I need to do a couple of hypothesis tests to determine what my final model should be (I'm aware of the debate over model simplifaction and so on, let's just say that in this case I'm pretty sure that you'd end up with the same answer whatever you did and if I use a hypothesis testing approach rather than, say, AIC-based model selection I'll at least have consistency with some other analysis). Reading around I find that I need to test for overdispersion but I can't find a clear description of how to do this - can anyone enlighten me? Assuming there isn't a problem with overdispersion, am I OK to use the LRT that anova() gives when I compare a pair of models to test ?

Thanks for any help, I apologise for my numpty-ness but I need to get this done soon and it's not exactly the easiest thing to work out.

Rob


School of Biological and Chemical Sciences
Queen Mary, University of London

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