Dear SPM authors and users,
I was working on the statistical power analysis described in "Detecting
activations in PET and fMRI:levels of inference and power", Neuroimage 40,
223-235 (1996). In page 227, under the topic "A Power Analysis" it is said
that (sigma) is the amplitude of the signal. Is the fMRI time course signal
meant by "the signal"? If so, is (sigma) the peak to peak amplitude
variation of this signal or is it the standard deviation of the fMRI time
signal in the activated region? Or is it the standard deviation of the peak
to peak variations of all suprathreshold voxels? An explanation will be
greatly appreciated.
Thanks,
Tugan Muftuler
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L. Tugan Muftuler, Ph.D.
Research Imaging Center
Irvine Hall 164
University of California
Irvine, CA, 92697-5020
Tel: (949) 824-6290
fax: (949) 824-3481
E-mail: [log in to unmask]
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