I have been experimenting with 3dReHo and it appears that using the ReHo command creates a large amount of blur, and I am wonding if that is accurate? My processing stream follows the pubs out there, acquiring ReHo and then subsequently blurring.

My commands are:
3dReHo -prefix reho_test -nneigh 27 -inset reho_rest_blur+tlrc
3dmerge -1blur_fwhm 4.0 -doall -prefix reho_blur_rest reho+tlrc

Using FWHMx:
3dFWHMx -detrend -mask res_reho_mask+tlrc -input reho_blur_rest+tlrc
# 13.2276 13.5527 12.8075

And without the blur its
3dFWHMx -detrend -mask res_reho_mask+tlrc -input reho+tlrc
# 9.83238 10.4292 9.55512

This combined blur creates a much larger requirement for multiple comparisons correction in clustersim (larger than appears required in the ReHo pubs out there...). Thoughts? Help? Should I be using a different estimate of noise for this calculation?

Thanks for the help!