I know that someone else has just posted a question on this topic, but I'm hoping that I can get an answer related to my format. I've used the design from the FEAT in detail page showing that EV1 contains the information for pre or post (-1 or 1), and the rest of the EVs used to account for within subject variance, one EV per subject. I want to know whether the difference between pre and post is modulated by a covariate score I have for each subject taken at pre. My thought is to modify EV1 or create a new EV with the demeaned measures entered as pre (replacing all the -1's with my covariate), and retain all the pst entries as ones.
Standard
EV1 EV2 EV3 EV4
-1 1 0 0
-1 0 1 0
-1 0 0 1
1 1 0 0
1 0 1 0
1 1 0 1
Contrasts EV1
pst-pre 1
pre-pst -1
Covariate
EV1 EV2 EV3 EV4
-1 1 0 0
-1 0 1 0
-1 0 0 1
-.3 1 0 0
.1 0 1 0
.2 1 0 1
Contrasts EV1
pst-pre_w_cov 1
pre-pst_w_cov -1
Does this sound right?
Thank you,
David
|