I wish to know how “cespct.nii.gz” is computed in selxavg3-sess. I thought it computes something like a relative change like: 

cespct = (contrast-baseline)/baseline*100, 

but I cannot figure out what was taken for the baseline. I thought it could be mean beta for constant terms (0-th polynomial) for each run, but my calculation was different from cespct.

I would take average intensity for each voxel I would greatly appreciate a detailed explanation how the program computes it.

Best regards,