Dear Christy,
> I used a fairly small smoothing kernel at the first level (voxel size
> [2 mm] x 2). I'd like to get my data in line with other published
> reports (10 FWHM or so is what I seem to see reported fairly often).
>
> Say I want to approximate the 10 FWHM-size kernel. Do I now use one
> that's 2.5 mm? Smaller? Bigger? Or is there some value (other than
> 10) that seems to result in better sensitivity at the second level?
The approximate rule is
FWHM = sqrt(FWHM1^2 + FWHM2^2)
In your case
FWHM2 (the second level FWHM) should be about 9mm
sqrt(10^2-4^2) = 9.1652
I hope this helps - Karl
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