Dear SPMers,
I am confused about the meaning of positive and negative effects attribute in the
SnPM setup. When conducting a paired t-test,2conditions,1 scan/condition you
are asked for positive or negative effects. If one condition is A and one is B then
what exactly is going on when choosing the positive or negative effects?Also,
should i use the results from both positive and negative or just only from one of
them?Finally,is smoothing variance necessary for MEG volumetric images if the
degrees of freedom is less than 20 df...is there a correlation between df and
smoothed of variance? do the residual df count as df???
Thanks,
Haris
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