[R-sig-ME] Random-effects variance-covariance matrix in lmer?

[m@tthi@s@suter m@iii@g oii @groscope@@dmi@@ch]

Hi all

I'm looking for a way to specify a more complex variance-covariance matrix for the random effects in lmer(). For example, in lme() (nlme package), there are the pdMat classes to specify e.g. a compound symmetry (pdCompSym) or a multiple of an identity (pdIdent) structure for the variance-covariance matrix of random effects. Is there a possibility to code an equivalent for lmer()? I'm specifically interested in "compound symmetry" and "multiple of an identity".

I assume that Douglas Bates or Ben Bolker have a distinct answer on that.

Thanks in advance,
Matthias


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Matthias Suter, Dr.sc.nat.
Forage Production and Grassland Systems

Agroscope
Reckenholzstrasse 191, CH-8046 Z�rich

Phone +41 58 468 75 90
Fax      +41 58 468 72 01
matthias.suter using agroscope.admin.ch
www.agroscope.ch
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