Dear Experts
I want to compare fMRI activity between three groups consisting of twins.
I want to be able to account for both non-independence between and within groups and unequal group size. We have performed fMRI using four paradigms assessing different domains of emotional processing.
The individual twins are grouped according to personal and co-twin history of affective disorders:
1) Control Group: Both twins have no personal history of affective disorders. Both twins in a twin pair are in the same group. N=29.
2) High Risk group: The healthy co-twins of twins with affective disorder. Only one twin from a twin pair is eligible in this group. N=33.
3) Affected Group: Twins with a personal history of affective disorder. Either the affected twin form a pair discordant for affective disrders or both twins from a twin pair concordant for affective disorders. N=63.
Would randomise/permutation testing be the best method of comparing these groups or would you recommend another approach? Is it possible to account for non-independence in traditional FEAT group analysis?
Looking forward to you response!
Best Regards
Iselin Meluken
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