Thanks Steve! I think i understand the last part. i thought using max or
mean or median was an arbitrary choice and susceptible to outliers and so i
chose 90th percentile value.
However, about the model, i'm not sure what you mean. Like i said in my
previous post, i ran GLM for all individual runs at the 1st level using same
time series model. At 2nd level i combined the 2 runs for each session and
for each subject using fixed effects analysis. At 3rd level, i ran paired
group difference between all session1's and Session2's. Is this not the
correct model to see if there are any significant differences between the
sessions?
Another model to compare sessions would be to specify Sess1-Sess2 contrast
at individual level and do a group mean. Are the 2 models conceptually same?
The latter seems to give less conservative results than the former.
-Vish
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