[R] crossed random fx nlme lme4

[Douglas Bates]

On 7/13/05, Simon Blomberg <blomsp at ozemail.com.au> wrote:
> At 09:35 AM 14/07/2005, Emilio A. Laca wrote:
> >I need to specify a model similar to this
> >
> >lme.formula(fixed = sqrt(lbPerAc) ~ y + season + y:season, data = cy,
> >      random = ~y | observer/set, correlation = corARMA(q = 6))
> >
> >except that observer and set are actually crossed instead of nested.
> 
> Does this work for you? (following P&B pp 162-3 and an R-help archive
> search on "crossed random effects")...
> 
> fit <- lme(sqrt(lbPerAc) ~ y * season, random=list(pdBlocked(pdIdent(~y),
> pdIdent(observer-1), pdIdent(set-1))), correlation=corARMA(q = 6), data=cy)
> 
> lme isn't very well set up for crossed random effects. It's easier in lmer.
> I don't think lmer can handle alternative correlation structures yet,
> though. (Prof. Bates?)

Exactly.  Thanks for the summary.

> 
> HTH,
> 
> Simon.
> 
> 
> >observer and set are factors
> >y and lbPerAc are numeric
> >
> >If you know how to do it or have suggestions for reading I will be
> >grateful.
> >
> >
> >eal
> >
> >ps I have already read Pinheiro & Bates, the jan 05 newsletter, and
> >several postings.
> >
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> 
> Simon Blomberg, B.Sc.(Hons.), Ph.D, M.App.Stat.
> Centre for Resource and Environmental Studies
> The Australian National University
> Canberra ACT 0200
> Australia
> T: +61 2 6125 7800 email: Simon.Blomberg_at_anu.edu.au
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