Hi again Andrew - many thanks for your clarification ! I do however have a couple of follow-up questions re Q1 and Q4.

Q1 - The reason I queried this was because NBS did not actually generate a rank deficient warning / error when I performed the analysis with design matrix (b). I have appended the full .txt for you to inspect. Should it actually be complaining ?

Q4 - I was thinking perhaps a change in results more from no significant network to potentially an emergent subnetwork after restricting number of ROIs - Is this a possibility following reduction in multiple comparisons ? Please correct me, I think I am not understanding the mechanics of NBS - but is the likelihood of finding a statistically significant cluster dependent at all on the size of input correlation matrices / number of individual edges ? Is the statistical testing not performed on the resultant component ie cluster with each permutation, circumventing the multiple comparisons issue entirely ? Or would it actually effect outcome if size of cluster is set to extent instead of intensity (what I have been using) ?

Please advise. Sorry and many thanks (also Happy New Year) - Athina.