[R-sig-ME] lme4 versus nlme

[Kevin E. Thorpe]

I'm a bit confused.

I have started reading Pinheiro and Bates, which is excellent.  I am
trying to rationalize when one would use lmer() and when one would use
lme() (I know lmer() is not covered in the book).

I have read a number of the treads about why p-values have been taken
out of lmer() stuff.  Naturally, they still exist in nlme.  Presumably,
I should not trust those p-values either.

The problem still remains that I am encountered more and more situations
where it seems I need a mixed model.  The investigator wants to know if
the groups differ.  What is the recommended approach to answering those
kinds of questions?

Thank you,

Kevin

-- 
Kevin E. Thorpe
Biostatistician/Trialist, Knowledge Translation Program
Assistant Professor, Department of Public Health Sciences
Faculty of Medicine, University of Toronto
email: kevin.thorpe at utoronto.ca  Tel: 416.864.5776  Fax: 416.864.6057