Hi Dr Martin
I want to study the change in cortical thickness overtime in one group of subjects.

I have only one group of subjects who scanned multiple times ( two time points and more)

I followed the pipeline exactly as in wiki.

I want to inquire about  X in this case . Is it supposed to be 1 ( one group)

In wiki they used the follwoing x=[ones(length(M),1) M M(:,1).M*(:2)] how this formulla will be for one group of subjects?