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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Nicholas Balderston
April 08, 2019 12:38PM
Hi everyone,

I have analyses that were done in 3dMVM, which give me f statistics. I am trying to write a script that thresholds these maps using a p-value and a minimum cluster size, using the 3dclusterize command. I was always under the impression that I should use a 2-sided test for these f-values, because the underlying contrast could be bi-directional (i.e. exp > control or control > exp). Is this standard practice?

2-tailed seems to be the default in the afni GUI (e.g. F(1,27) = 13.61; p = 001). However, if I try to replicate this behavior in 3dclusterize by using a 2-sided test, I get the following error:

** FATAL ERROR: You are asking for multisided clustering on a single-sided stat!

Other than using a 1-sided test with p=p/2, is there a way to override this error?

Thanks,
-nick
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Subject Author Posted

Possible Bug: Default behavior in 3dclusterize vs. afni GUI

Nicholas Balderston April 08, 2019 12:38PM

Re: Possible Bug: Default behavior in 3dclusterize vs. afni GUI

rick reynolds April 08, 2019 04:25PM