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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
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



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