Hi FSLers
I'm trying out a contrast that uses the Calhoun (2004) method of
incorporating the temporal derivative using the formula:
sign(PE1)*sqrt(PE1^2+PE2^2) where
PE1 == standard EV fit
PE2 == temporal dv of EV
I then divided by the SEM of the residuals (res4d.nii.gz). The values do
not look like t-stats, with the range being something like -250 to 250.
Now I'm faced with the really basic question: how are the PEs converted
to t's and z's? I know the conversion is supposed to be pretty
straight-forward and it states on the feat page that 'To convert
estimates of parameter estimates (PEs) into statistical maps, it is
necessary to divide the actual PE value by the error in the estimate of
this PE value', which is what I thought I did when dividing by the SEM
of the res4d file. What's goin' on?
Thanks
Nick
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