[R] crossed random fx nlme lme4

Simon Blomberg blomsp at ozemail.com.au
Thu Jul 14 04:45:10 CEST 2005

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?)



>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
>ps I have already read Pinheiro & Bates, the jan 05 newsletter, and
>several postings.
>R-help at stat.math.ethz.ch mailing list
>PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html

Simon Blomberg, B.Sc.(Hons.), Ph.D, M.App.Stat.
Centre for Resource and Environmental Studies
The Australian National University
Canberra ACT 0200
T: +61 2 6125 7800 email: Simon.Blomberg_at_anu.edu.au
F: +61 2 6125 0757
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