Dear SPM-list readers,
in an experiment we ran, an intrinsic physiological parameter is interpreted
like a stimulus function in an event related design, which means we convolve
it with the hrf and feed it into SPM as a user specified regressor.
Since we could not predetermine this 'stimulus' we at least want to assess
the efficiency of the 'design' retrospectively by calculating the variance
of the convolved parameter after also applying the SPM filters set in the
repsective analysis.
Now that we have the numbers (range .15 to .42, 10 subjects), what do they
tell us besides that we can compare the subjects' runs with one another? In
other words, are there absolute values stating like 'this is a
good/efficient design' or 'I wonder you could detect an acitvation at all'?
Thank you.
Helmut Laufs
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Helmut Laufs ([log in to unmask])
Johann Wolfgang Goethe-Universität
ZNN, Klinik für Neurologie
Haus 95, Raum 031
Schleusenweg 2-16
60528 Frankfurt / Main
Tel.: +49-69-6301-4341
Fax : +49-89-244310612
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