I have a quick question about thresholding Bayesian stats:
The SPM5 manual instructs the use of the formula below for setting a PPM
threshold (in this case giving an output of 4.7), however, it seems a bit
high, thresholding out all signal increase.
sf = max(SPM.xBF.bf(:,1))/SPM.xBF.dt, threshold=(1/sf)
The un-thresholded contrast file itself looks spatially similar to the
output from the standard SPM analysis, but the max value is 4.12 (compared
to 4.7 calculated as the threshold). The standard analysis gives out a very
healthy corrected activation map so I'm not entirely sure what I'm doing
wrong here?
Any help would be greatly appreciated.
All the best
Jonathan
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