Hi,
In SPM, I have noticed that when multiple amplitude modulators (or parametric modulators, as they call them) are assigned to a regressor, each successive modulator that you add is orthogonalized with respect to the first modulator. This can lead to different results depending on how you order the input of your modulators.
I was wondering, does AFNI do something similar? Does the order of the modulators that you input affect your results at all? I ran some simulation data in one order of modulators and in another order, and it didn't seem to affect the results at all. I just wanted to check and make sure.
Thanks!
-Andy
