If you have repeated-measures, you should not be entering covariates as covariates aren't going to change the relationship between the actual measurements and if you have 1 covariate value per subject, it will be collinear with the subject columns. If there are only 2 repeated-measures, it would be easier to just create a difference image and then do a one-sample t-test with a covariate.

If you have a time-varying covariate, then you should be running a linear mixed effects model.

Best Regards,

Donald McLaren, PhD

On Tue, Aug 11, 2015 at 1:57 PM, Joelle Zimmermann <[log in to unmask]> wrote:

Hi SPMers,

I'm setting up a second-level model, and I want to input a Covariate in the factorial design specification.

This is more of a technical question, what is the format in which I can input the Covariate vector? I'm not entirely clear on this based on the documentation in the GUI.

There it just says to "Enter the covariate values per subject (ie all for subject 1, then all for subject 2, etc)."

I have only 1 covariate value per subject, so can I just enter all these numbers in a list ie. [Sub1Covariate, Sub2Covariate, Sub3Covariate...] ?

Thanks,
Joelle