Dear AFNI experts,

I am using 3dTproject to do nuisance regression. Sometimes we combine different fixed 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" or "0.012 - 0.028" Hz combined with the mentioned fixed regressors.
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 with different regression models: i) The first one was done using fixed regressors (movement, physiological recording, white matter, etc.) ii) and the second was done only with a 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.

Best regards,
Karel