Dear SPMers/SnPMers,
I am doing a non-parametric second-level analysis (12 con images) with
SnPM-99.
I understand that there is no "SVC" option in SnPM, however could I
still anyhow benefit by having a spatially-constrained hypothesis
about activation?
For the sake of experiment I tried to perform an SnPM99 analysis on
con-images previously masked by a VOI. I noticed that the "critical
threshold" reported at the bottom of Table is lower for the VOI
analysis then for the whole brain analysis, both were done with the
same variance smoothing, number of permutations, thresholds (voxel
p<0.05, no extent threshold), etc. Moreover the VOI-based analysis
revealed a significant activation that did not show up during the
whole-brain analysis.
However I doubt that this is the right thing to do... :/
any comments please?
thanks!
Victor
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Victor Vorobyev
Centre for Cognitive Neuroscience
Department of Psychology
University of Turku
Finland
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