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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Wolfgang Gaggl
February 02, 2004 05:11PM
First of all, nice job with the AFNI homepage.

I'd like to verify, if I'm thinking correctly here:

I'm doing an experiment, where I count the number of active voxels above a certain correlation threshold and try to calculate the theoretical p-value (without taking the lack of independece between tests into account).

I have 24 volumes in a series (sampling rate of 10sec). I'm omitting the first image, so I'm left with 23. This would then get me df=22 for the correlation and a critical correlation of 0.4 at p<0.05. Clustering my voxels into groups of at least 3 neighboring voxels improves my p-value to 0.000125, applying unadjusted Bonferroni corrections for ROIs of about 80 voxels gets me a p-values of 0.01 for the test. Any objections?

Thanks,
W.
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Voxelcount Significance Levels

Wolfgang Gaggl February 02, 2004 05:11PM