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Dear SPM, I have an elementary smoothing question that I couldn't find an answer to in the archives. I have 4 participants, all of whom started with voxel sizes that had been resampled to 4 x 4 x 4 mm during realignment. I applied a smoothing kernal of 12 mm FWHM and ran models on each participant's data. When I look at the results, at the bottom of the results page, each participant has a different estimated smoothness. Participant 1: estimated smoothness (mm) = 11.9, 12.3, 11.5 mm = 3.0, 3.1, 2.9 (voxels). Participant 2: estimated smoothness (mm) = 19.0, 20.0, 17.5 mm = 4.8, 5.0, 4.4 (voxels) Participant 3: estimated smoothness (mm) = 14.0, 14.4, 13.1 mm = 3.5, 3.6, 3.3 (voxels) Participant 4: estimated smoothness (mm) = 15.5, 16.1, 14.1 (mm) = 3.9, 4.0, 3.5 (voxels). 1) Is this normal? If so, can I just ignore it? 2) If not normal, assuming that most of the time I didn't make any typographical errors, does anyone have any idea what might account for these differences? Thanks, Christy