Hi,
my dataset contains 15 subjects, each with 2 sessions and with 2 runs in
each session. My aim is to find if the paradigm i used gives reproducible
results or not(i.e 2nd session is the replica of the 1st session). so i ran
1st level GLM analysis for each run. at the 2nd level i did a Fixed effects
analysis combining the 2 runs for each session and each subject(i.e i have
21 session1 cope images and 21 session2 cope images). At the 3rd level, i
did a paired comparison between the 2 sessions using FLAME-1. i did not get
any significant differences. then i found the group mean of each session
using flame and i ran featquery with an ROI and found that the 90th
percentile COPE and VARCOPE values of the two sessions were quite different.
90-percentile Session1 Session2
COPE 38 25
VARCOPE 19 20
Even though the variances are similar the COPE is changing significantly.
therefore should'nt i get significant differences between sessions at the
3rd level paired comparison analysis? any suggestions as to why this might
not be the case. also, would this 3 level analysis be an appropriate method
of assessing the reproducibility of activation in a particular ROI?
Thanks!
-vish
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