Yes, you can add a covariate to this model. Just make sure that:
1 - it is demeaned
2 - it is not the same as one of the factors or a combination of them (as this would make the design rank deficient)
If your confound varies with subject then the second condition should be met, in which case just make sure that you demean the values before entering them into the EV.
All the best,
> On 28 Aug 2017, at 10:58, Kim TRAN <[log in to unmask]> wrote:
> Dear FSL expert,
> I want to perform an ANOVA model for 2-groups, 2-levels per subject (2-way Mixed Effect ANOVA) following fslwiki GLM. Otherwise, I also doubt about some confounding factors, could I add them to model as covariate? I really appreciate any advice you can provide.
> Best regard,
> Kim TD