Hi Rick et al-
I've had a similar problem with 3dFWHMx underestimating smoothness. In my case, it seems to happen only when I use the 'detrend' option. I'm not sure whether this is a bug with detrend, or perhaps detrend is inappropriate when using data that doesn't have anatomical detail (i.e. residuals.)
Here's example output, and I'll upload some data momentarily.
3dFWHMx 1008.rest.r1.errts+tlrc;3dFWHMx -detrend -input 1008.rest.r1.errts+tlrc
++ 3dFWHMx: AFNI version=AFNI_2011_12_21_1014 (Aug 9 2012) [64-bit]
++ Authored by: The Bob
*+ WARNING: removed 276486 voxels from mask because they are constant in time
6.80059 7.0549 6.13733
++ 3dFWHMx: AFNI version=AFNI_2011_12_21_1014 (Aug 9 2012) [64-bit]
++ Authored by: The Bob
*+ WARNING: removed 276486 voxels from mask because they are constant in time
++ detrending start: 11 baseline funcs, 126 time points
++ detrending done
3.68432 3.78866 3.5248
Hope this helps isolate the issue, and look forward to guidance!
Cheers,
Josh
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Josh Powell
Center for Health Behavior Neuroscience
University of Kansas Medical Center