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
January 23, 2017 09:55AM
Pascale,

3dMVM does not account for heteroskedasticity because the impact is usually not substantial. Especially when the number of subjects in the two groups is roughly equal, the 3dMVM (as well as the typical two-sample t-test) approach is robust to the presence of unequal variances. However, if this is really a concern, for a test comparing *two* groups, you can use 3dttest++ -unpooled to perform Welch's t-test: [en.wikipedia.org]

Gang



Edited 2 time(s). Last edit at 02/28/2017 04:48PM by Gang.
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Subject Author Posted

heteroskedasticity

Pascale January 19, 2017 07:37AM

Re: heteroskedasticity

gang January 19, 2017 02:15PM

Re: heteroskedasticity

Pascale January 19, 2017 05:39PM

Re: heteroskedasticity

gang January 23, 2017 09:55AM