Umi,
I'm quite sure the SPM.xVol.FWHM for a group random effects result is
for the group residuals, and not an average of each individuals FWHM.
I'm curious about the idea you read that the "right" way to do this is
to average the individuals FWHM. I may be wrong, but if the smoothness
is used to calculate a significant cluster size in the group random
effects result, it seems logical to use the residuals of the group
random effects result to calculate that smoothness, and not an average
of the individual subjects smoothness, since the random effects
analysis is not an average. I'm interested to know where you read
that.
Jim
On 8/27/13, Umi V. <[log in to unmask]> wrote:
> Also just to clarify, I am considering smoothness converted to mm, not in
> voxels, so I can't attribute discrepancies to unit differences.
>
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