AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

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rick reynolds
August 23, 2019 05:01PM
Hi Heather,

After pondering for a while, those numbers do not seem out of the realm of reasonableness. Your blur level is pretty low: 3.125 mm voxels, with a final blur (not an added blur) of FWHM = 6 mm.

That would be akin to adding a blur of FWHM = 3 mm, or so, which is very small.

So if the final FWHM is supposed to be 6 mm (and that is estimated with a standard, Gaussian ACF), you are getting a mixed-model ACF FWHM estimate of 6.7 mm, which seems to be in the correct ballpark.

To be sure, note what the 4 parameters are. The first is the fraction of the Gaussian term in the ACF model (so the linear fraction is .43 = 1-.57). The Gaussian term is 2.5 mm (small), and the linear term is 7.35. But that leads to a reasonable FWHM of 6.73 mm.

Also to be sure, are you applying a brain mask in this computation?

- rick
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Subject Author Posted

3dLME cluster thresholding

heatherb August 21, 2019 12:32PM

Re: 3dLME cluster thresholding

rick reynolds August 23, 2019 05:01PM

Re: 3dLME cluster thresholding

heatherb August 30, 2019 10:52PM