Hi Rick,
Thanks so much for your response! I guess I'm just confused about which output to use for my multivariate analysis then since I'd ideally like one file that just has motion and WMe/Svent regressed out with no (or minimal) detrending (like an allruns file just with the motion and nuisance signals regressed out). It seems like no matter how lenient I'm being in the preprocessing, the errts dataset is still too sparse. I even tried polort -1 and regress_no_motion with the assumption that the only thing in the fitts file would be the nuisance signals I was modeling out and the rest would be in the errts. I'm probably just missing something obvious conceptually. Sorry that I'm a bit slow on this!
Thanks,
Laura