Hola,

First Question: I ran afni_proc.py and applied the full_mask to the regression. However, I realized afterwards that the full_mask doesn't do a great masking job because some of my participants have ghosting. So, now that I want to do the second level analysis, I am trying to run 3dttest++ and apply a mask of the tailarach epi template. I get the following error.

-mask doesn't match datasets number of voxels

What does this mean and does it indicate a deeper problem with the analysis?

Second Question:
When I run 3dttest++ without trying to apply a mask, it runs without any fatal errors, but tells me for each subject that it skips approximately 94377 voxels completely for having constant data.

a) This seems like an absurdly high number, does it not?
b) Does this (absurdly?) high number of skipped voxels have anything to do with the issue discussed above in the first question?
c) What does it mean to skip voxels for having constant data at the second level of analysis? Is that saying that if every participant has the same beta value for a given voxel, that voxel will be skipped? What is the purpose of that?

Thank you mucho!!!