Hi Sam,

Either way (ZERO or KILL), 3dTproject is just projecting out all of the components you are asking it to. But when censoring, there are 3 choices for how the output is constructed. Assume there are 200 time points initially, and 25 are being censored out. Then:

ZERO: the output will still have 200 time points, and the time points that were censored will be exactly 0
(note: this is the effect of running 3dDeconvolve and using errts as the projected result)

KILL: the output will have 175 time points, where the censored points are actually removed

NTRP (interpolation): the output will have 200 time points, where the censored data gets created via interpolation of the temporal neighbors

If afni_proc.py is used in resting state analysis, it uses ZERO, both to mimic 3dDeconvolve, and to keep the input and outputs the same lengths. Note that all-zero volumes in the result would not affect correlations.

- rick