[R-sig-ME] Running repeated measures in lme4

[Ben Bolker]

Emma Stone wrote:
> Dear all,
> 
> I wander if you can help.
> 
> I am running a repeated measures model with lmer.I have 8 sites, at each I 
> conducted an experiment with treatments which have 4 levels. Each treatment 
> was conducted only once per site, but each site has one of each of the 
> treatment levels so it is balanced. Obviously the treatments within sites 
> are the repeated measures component, and I want to look at differences 
> between treatments within sites, I am not really interested in the site 
> group effect but need to incorporate it. So I have set up my model as 
> follows:
> 
> model1<-lmer~(minutes~treatment+(treatment|site), data = data)

  This model fits a site by treatment interaction, which you don't
have enough information for since you don't have replication.  I believe
you want

model1<-lmer~(minutes~treatment+(1|site), data = data)


-- 
Ben Bolker
Associate professor, Biology Dep't, Univ. of Florida
bolker at ufl.edu / people.biology.ufl.edu/bolker
GPG key: people.biology.ufl.edu/bolker/benbolker-publickey.asc