Bioequivalence and Bioavailability Forum

Hi d_labes,

❝ what was the question?

The question is, how to fit a relevant model with lme and how to extract relevant variance components in an easy way? (as in, easier than in the post linked to).

❝ You may find here some hints for using nlme/lme() in evaluation of replicate cross-over designs.

I read the post many times since you originally posted it
But I am none the wiser even after reading it many times. So, I feel I have an ok understanding of the mixed model, and I have an ok understanding of which variance components I can reasonably ask for; the next step is then to ask lme to get me what I want in an intuitive fashion. That last thing is not easy, and books like Pinheiro & Bates do not really get me there.

For example: I prefer to play with variance components directly without involvement of rho (correlation) for the covariance of T and R. Where do I start? Playing around with weights, correlation structure, etc may get me what I want (see the two threads linkeda above), but that stil does not mean I am using lme meaningfully or optimally, I feel.