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
August 21, 2012 03:01PM
> I just noticed that running the following command yields a dataset with 34 degrees of freedom
> in each of the t-stat subbricks. Is this because I didn't use -unequal_variance? Is it going to
> inflate my t-statistics? Should I be worried?

In this regard 3dMEMA is pretty much like two-sample t-test in which the statistics in the results are based on the pooled variance. Even if the equal variance assumption is violated, usually the impact is minor. And I would not worry about it. You could run another analysis with option -unequal_variance and see how they compare.

Gang



Edited 2 time(s). Last edit at 08/21/2012 06:07PM by Gang.
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Subject Author Posted

3dMEMA degrees of freedom issue

Isaac Schwabacher August 21, 2012 02:33PM

Re: 3dMEMA degrees of freedom issue

gang August 21, 2012 03:01PM

Re: 3dMEMA degrees of freedom issue

Isaac Schwabacher August 21, 2012 04:42PM