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

History of AFNI updates  

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July 07, 2015 08:57AM
Hi Walker,

I am glad the averages are coming out to be
reasonably similar.

Regarding the LSS results, you are likely seeing
that inter-trial variance is generally very large,
relative to inter-subject variance of the averaged
betas.

Particularly with short events (as would be modeled
with GAM), the pseudo-time series of event betas is
not going to be like a flat line at the mean (which
would be wonderful, were it to happen). It is
likely going to be as noisy looking as the original
data. Plot it and see.

That high variance, when viewed as repeated measures
in your ANOVA, will drive down the significance.

This is exactly why in FMRI, one generally uses many
events (20-25?) to estimate a single beta.

- rick
Subject Author Posted

Modeling Each Condition vs. Each Trial

wped July 02, 2015 03:45PM

Re: Modeling Each Condition vs. Each Trial

wped July 06, 2015 04:30PM

Re: Modeling Each Condition vs. Each Trial

rick reynolds July 07, 2015 08:57AM