[R] Specify correlation structure in lme4

[Ben Bolker]

Thomas Stewart <tgstewart <at> gmail.com> writes:

> If I have the mixed-model with
> 
> lmer( y ~ x1 + x2 + (1 | id) + (z1 | w ) , ... )
> 
> there is no way for me to specify a correlation structure for the random
> effects? Right?
> 
> If I want to specify correlation structure then I need to use lme in the
> nlme package?  Right?  Crossed Random effects are coded with the pdBlocked
> syntax?  Right?

   Right on all counts (see Pinheiro and Bates 2000 for details
of crossed-effect coding with pdBlocked). In general it might
be better to send these types of questions to r-sig-mixed-models
instead of r-help ...