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
August 23, 2004 05:15PM
Hi Toe,

Yes, you are correct: the number of 0.3622 at that particular voxel means there is about 0.36% change/difference for that difference term (Mcorvincor).

The significance of a term (difference in this case) is NOT based on its value, instead it is decided by its t value relative to its standard deviation. In other words, it is the ratio of the term value (effect amplitude) to the variability of its effect. Therefore it is this t value relative to the student distribution, which is 4.353, not the term value of 0.3622, that signifies the significance at the particular voxel. If you feel that the percent signal change of 0.3622 is small, that is because its variability (standard deviation = 0.0832) is also relatively very small.

Gang
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percent change and group analysis

teodora August 23, 2004 04:08PM

Re: percent change and group analysis

Gang Chen August 23, 2004 05:15PM

Re: percent change and group analysis

Lisa Eyler August 24, 2004 07:56PM