Hello,
I have a question about setting up a multi-level model in NLME. I have the
P&B book, but I am still having trouble specifying the model. I am using
the most recent version of NLME on R 1.3.0. I was referred to NLME after a
previous query on multi-level models. Yet, I think part of my confusion is
that I do not have a mixed model as far as I can see. I have random effects
nested within levels of a random effect?
The problem is this: I have a sample of classes (class being the nesting
factor). Within each class I have a sample of students. I have separate
random effects models at each level. That is, at the class level, I have:
random=~class_size+number_teachers+class_length
and at the student level I have:
test_score~treatment+experience+age.
What I want o assess is the contribution of class level variables
simultaneously with individual level variables on test scores.
Now, my problem is specifying them both as a random effect. I tried to use:
random=list(class=~class_size+number_teachers+class_length,
=~treatment+experience+age)
But NLME did not like the second argument, no surprise, I really didn't
expect it too as random=list is used for multiple grouping factors. Yet, I
can't figure out how to specify this. Can someone offer me some advice on
how to fit this model.
Thank You.
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