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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carl
March 25, 2003 06:11PM
Hello

I have an experiment with 9 conditions and i want to see the overall effect of 7 of these conditions. I used the -GLT option on 3dDeconvolve with a multiple linear combination (7) to create an omnibus F stat but now need to put a sign on it to see what the direction of activation is. I used the script :

3dcalc -fscale \
-prefix signF \
-a52 Group+tlrc \
-b39 Group+tlrc \
-c41 Group+tlrc \
-d42 Group+tlrc \
-e43 Group+tlrc \
-f45 Group+tlrc \
-g47 Group+tlrc \
-h49 Group+tlrc \
-expr 'a*step(step(b)+step(c)+step(d)+step(e)+step(f)+step(g)+step(h))' \

where a=the f stat and b-h are the COEFS for each of the individual conditions that i would like to include.

However, the above script only gives me positive values and not the negative ones that one would associate with deactivity.

Could you please advise me on where the above script went wrong ?

Many thanks

Carl
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Subject Author Posted

how do i get a signed f stat ?

carl March 25, 2003 06:11PM

Re: how do i get a signed f stat ?

Craig Stark March 26, 2003 09:19AM

Re: how do i get a signed f stat ?

Ziad March 26, 2003 11:04AM