Dear AFNI experts,

I am using 3dTproject to do nuisance regression. Sometimes we combine different types of regressors (movement parameters, physiological recordings, etc.) and also a band pass filter. The problem appears when I try to band pass at "0.002 - 0.01" and "0.012 - 0.028".
It seems that band passing at those frequency ranges use at least more than 90% of the D.O.F from the data set. Then, if I have more regressors (movement parameters, physiological recordings, etc.) it is not possible to do the regression because the number of regressors exceeds the number of time points.

Error message:

+ Block #0: 250 time points -- 243 stopband regressors
++ 1 Blocks * 5 polynomials -- 5 polort regressors
 + -- 14 other fixed ort regressors
[7m** ERROR:[0m total number of fixed regressors (262) is too many for 250 retained time points!

How could I deal with this problem if I want to keep using 3dTproject?

Also, in a hypothetical case, if I am interested to compare results between two samples. In the first sample nuisance regression was done by using fixed regressors (movement, physiological recording, white matter, etc.) and a band pass filter in a certain frequency range. On the other hand, in the second sample nuisance regression was done by using only the band pass filter.

Are these results comparable considering that the conditions in the regressions were different?

If you could help me with these queries, I would greatly appreciate it.

Thanks in advance,
Karel