dear SPM experts,
We have a design with one group of 15 subject and a single covariate regressor.
Is it possible to include in the design matrix both a factor subject and a covariate?
If possible, what shuld be the weights for the subject factor while testing for the effect of the covariate?
1. ones(1,15)*[1/15] 1
2. zeros(1,15) 1
and for both we got "invalid contrast"