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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Kim Dalton
May 12, 2006 10:53AM
Is there a statistical advantage/disadvantage over using -gltsym in 3dDeconvolve to average across conditions in a factorial experiment vs. creating separate .1D files collapsing across conditions?

Example:

2 x 2 x 2 within subjects design with (only) eight trial per 8 crossed conditions - total of 64 ER trials.
To test the overall effect across all conditions (there is also a between subjects group variable) one could have a separate .1D file for each 8 conditions and:

1) use -glt_label 1 Average_Response
-gltsym 'SYM: +0.125*cond1 +0.125*cond2 ... +0.125*cond8'

or

2) create a .1D file with the time points for all 64 trials and use -stim_times 1 Average.1D 'GAM' or the like in 3dDeconvolve.

Which (if either) of these is statistically more powerful?

p.s. thanks again to Rick and Ziad for the AFNI workshop last week in Wisconsin!!
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3dDeconvolve & -gltsym

Kim Dalton May 12, 2006 10:53AM

Re: 3dDeconvolve & -gltsym

rick reynolds May 12, 2006 12:34PM