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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bob cox
November 25, 2002 03:01PM
One problem may be that 3dDeconvolve's baseline is b0+b1*(n-nfirst). This means that the b1 (linear) term does not have zero mean. You should account for this by using (b0+0.5*b1*(N-1)) for the denominator, rather than just b0. (Or you could use the "-polort 0" option to 3dDeconvolve to make the baseline model be a constant, but I don't recommend that!)

Also, if you actually want % change, you have to multiply your formula by 100, or it is fractional change. If you are doing this in 3dcalc, then I'd also recommend saving the data in floating point format, using the option "-datum float". This will avoid trying to scale the results to fit into a 16 bit short.

bob cox
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Subject Author Posted

% signal change after 3dDeconvolve results

serge November 25, 2002 10:43AM

Re: % signal change after 3dDeconvolve results

bob cox November 25, 2002 03:01PM

Re: % signal change after 3dDeconvolve results

Jim Eliassen November 25, 2002 03:35PM