Dear Esa,
> 1) I used The Full Monty.. model. After analysis I chose SVC and
> Search Volume... Image. Then I selected manually created mask image.
>
> 2) I tried explicit masking in The Full Monty... model using the same
> manually created mask image. Otherwise the Full Monty... model was the
> same as earlier.
>
> The statistics (Z-scores and p-values) were similar but not quite the
> same. Search volume and the number of resels were slightly different
> between SVC and explicit masking. The activated clusters were located in
> the same places and the number of voxels in each cluster were almost the
> same.
>
> What causes the slight differences between explicit masking and SVC?
There can be slight differences between the estimated p-values between
your analyses 1 and 2. As far as I can tell from Karl's code, he
estimates the smoothness within the VOI in the SVC routine based on the
smoothness estimate of the full volume. This means that the estimated
FWHM (and therefore resels and corrected p-values) between your two
analyses can differ slightly. I cannot explain your observation of
different search volumes, though.
>
> In my opinion, explicit masking can be used to visualize SVC
> results. Any comments on this?
Do you mean by this that one could visualize on the MIP only those
suprathreshold voxels belonging to the VOI?
Stefan
--
Stefan Kiebel
Functional Imaging Laboratory
Wellcome Dept. of Cognitive Neurology
12 Queen Square
WC1N 3BG London, UK
Tel.: +44-(0)20-7833-7478
FAX : -7813-1420
email: [log in to unmask]
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