HI all, In my design, I have factors A and B, and dependent variable DV, and the covariate variable is CV. It's a within-subject design so the subject variable is Sub. When I ran ANOVA, I used: anova=aov(DV~A*B+Error(Sub/A*B),data=data) What should I do to include the covariate CV to run an ANCOVA? Thanks! -- View this message in context: http://r.789695.n4.nabble.com/-tp4649272.html Sent from the R help mailing list archive at Nabble.com.