[R] confidence intervals for linear combinations when using lme

[Anna.H.Persson@astrazeneca.com]

Hi 

I really hope someone can help me.

I have just started to work with S-plus, and have not yet understood how it
really works. I am now trying to fit a mixed effects model with lme. My goal
is to compare four different groups, at several different time points, and I
therefore would like to create confidence intervals for linear combinations
of my estimated parameters (as I usually do with "contrast" or "estimate" or
"lsmeans" in SAS). I have now found out that the vcov-function in the
lme4-package could be of great help for me, but I do not know if I can use
lme4 when working with S-PLUS 6.1, or is it only for R. 

When I write 
>library(MASS)
I find lme3, where there is a vcov-function, but if I understand it
correctly it works with lm and not with lme...

If I can use lme4 with s-plus 6.1, what shall I do in order to install it on
my computer?

I am grateful for all help I can get?

best regards
Anna Persson