Hello all, I apply Repeated measures ANOVA for analyzing ERPs data. To do this I use lme() function and glht() for the post hoc analysis. I followed the very useful suggestions found in this help list but I have a problem. I do not know how to test the interaction between different levels of my predictors. Consider I have 2 predictors, the first one has three levels: A,B,C; also the second one has three levels:1,2,3. How can I investigate, for example, the interaction between A and 2? Thank you in advance for your help. Nicola