Hi Alfonso,

Thanks for all your amazing contributions. Looking at the answer you gave below, how would I test the same effects and interactions if I have 4 conditions, instead of just 2. For example, for the main effect of group, I would write [1 -1] in first column, in second column I don't know if instead of [.5 .5] I should write [.25 .25 .25 .25]? I would also like to test the effect of condition, and condition by group interaction.
Thanks again