Hello,

I am having some difficulty figuring out the output of 3dFWHMx on data from +orig space and how to use these data to generate AlphaSim results.

Here are the results from 3dFWHMx for the errts file from a 3dDeconvolve run.

errts_run1+orig (voxel size = 3.9 X 3.9 X 4.8mm): mean x, y, and z values = 4.7
errts_run1+tlrc (voxel size = 2 X 2 X 2 mm): mean x, y, and z values = 5.8
errts_run1_4mmFWHMblur+tlrc (Blurring carried out with 3dmerge after converting to tlrc space; voxel size = 2 X 2 X 2mm): mean x, y, and z values = 9.8

I will carry out my across-subject statistical tests (e.g., Ttests) on the 2x2x2mm_4mmblurred_beta values+tlrc files and want to use AlphaSim to calculate the minimum cluster size.

My first question is why there is already spatial smoothing in my +orig files.

My second question is which of these 3dFWHM values should I be using as the -fwhm value in AlphaSim.

Best,
Christine