Yes - that sounds correct Ed.

And if you would like to test the main effect of sex, you could simply average the connectivity matrices across the two time points for each subject, and then use the averaged matrices to test for a sex effect. I.e. a longitudinal design is not really needed to test for the main effect of sex because sex does not change between the two time points. 

Best wishes, 

Andrew

Originally posted by Ed Hutchings:

Hi Andrew,

Thanks very much for your reply. 

Just to be clearer about my design, I'm looking at changes in edge weight between two age groups. Some subjects are imaged in both age groups, most are not.

Since sex is unchanging over time, and is modelled by the within subject columns, I can remove the sex column from the design matrix. This leaves age, age*sex, and intra-subject dummy variables. To then test the main effect of age group I would use [1 0 0 ...]. Have I got this right?

Thanks for your help!