Greetings. Is it possible to extract the model matrix (Z) for the random effects from an lme object? For example, assume the model has two levels of random effects as in:
 
Y = XB + Zu + e
 
model.matrix() gives the matrix X only. For example:
 
> tt<-model.matrix(distance~age, Orthodont, random=~age|Subject)
> tt[1:10,]
   (Intercept) age
1            1   8
2            1  10
3            1  12
4            1  14
5            1   8
6            1  10
7            1  12
8            1  14
9            1   8
10           1  10
 
Thanks.
Harold

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