[R] lme4 - higher level

[Brian Perron]

Hello all,

I just started working with the lme4 package to estimate a multilevel 
logistic regression and am planning to use this package for a 
cross-classification / multiple-membership model.  I haven't found many 
worked examples and am trying to figure out how to add variables to the 
higher-level part of the model.  Consider the following example:

test.1 <- lmer(y ~ b1 + b2 + b3 + (1 | group), org.data)

This model shows a simple two-level nesting pattern -- for example, 
persons nested in groups.  If I have data describing the groups, such as 
the age or accreditation status of the group (or both), how would I 
include those variables in the model? 

I found a very nice description of lme4 by Bates describing the package 
in R News.  Is anybody aware of any other examples or resources that 
provide worked examples preferably with annotated results?

Thanks,
Brian