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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