[R] How to extract R{i} from lme object?

[Peng]

Hi, lme() users,

Can some one tell me how to do this.
I model Orthodont with the same G for random
variables, but different R{i}'s for boys and girls, so
that I can get sigma1_square_hat for boys and
sigma2_square_hat for girls.

The model is Y{i}=X{i}beta + Z{i}b + e{i}
b ~ iid N(0,G) and e{i} ~ iid N(0,R{i}) i=1,2
orth.lme <- lme(distance ~ Sex * age, data=Orthodont,
random=~age|Subject, weights=varIdent(form=~1|Sex),
method="ML")

I can see the numbers I need from summary(), but how
can I extract them? I tried several functions in nlme,
but I cannot find a correct one.

Peng

Peng Liu
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Peng Liu                      |
Division of Statistics        |
Northern Illinois University  |
De Kalb, IL 60115, USA        |
E-mail: pliu at math.niu.edu     |
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