Hello, I want to be able to create a design matrix with two factors. For instance, if I have:> t1 <- factor(c(1,1,2,2)); > t2 <- factor(c(1,2,1,2)); > design <- model.matrix(~ -1 + (t1+t2)); > design;t11 t12 t22 1 1 0 0 2 1 0 1 3 0 1 0 4 0 1 1 But the design matrix I want is: t1 t2 1 1 0 2 1 1 3 0 0 4 0 1 Actually, in general I'm struggling with the syntax for formulating a design matrix I can write down on paper. Is there a reference for this beyond the R documentation? Thanks, Paul