Hi everybody I am trying to move from SAS to R and there is a couple of things that I have not been able to obtain from the nlme3 module (mixed models) I want to compare the differences between different levels of a categorical variable in presence of a non-ignorable interaction compromising this variable. To do this I SAS gives you the possibility to extract predicted population margins (they call them least squares means or LS means) for each level of a categorical fixed effect in the model, so these values can then be used to perform multiple comparisons and look for meaningful differences between levels of a categorical fixed effect. I guess that in R I could do this manually by using the augPred() function for each possible combination and then performing multiple comparisons over these values but I just want to know if there is and already built-in function to do this. Also In SAS exists an option to "slice" the LSMeans output so you can obtain separated outputs for each level of the variable (test of simple effects). This is very handy when it comes to evaluate levels of nested and/or interaction terms. Is there sometihing similar available in R? Thanks for your help! Francisco _________________________________________________________________ http://messenger.yupimsn.com/