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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Gang Chen
October 10, 2007 03:36PM
> does AFNI take the absolute difference between two groups when
> computing a t-test when there is deactivation in one or both groups?

No, it takes whatever values from the input files without any manipulations.

> how do people handle negative values in their t-test results?

I don't know abou this.

> if there are voxels with zero values, and the t-test performs a voxel
> by voxel comparison, are some voxels with activation eliminated?

Not so sure what your question is about. Are you asking this: If those voxels with 0 values had nonzero values, might some of those voxels be identified as "activated"? If so, yes it is definitely possible.

AFNI Gang
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Subject Author Posted

t-tests

Mona October 10, 2007 02:51PM

Re: t-tests

Gang Chen October 10, 2007 03:36PM

Re: t-tests

Mona October 10, 2007 03:52PM

Re: t-tests

Gang Chen October 10, 2007 04:14PM