Hi Anderson,
Thanks for your explanation. Am I right to say that it appears the main difference with the second model vs the first is controlling for group differences and then examining the relationship between FA and behavioural scores on top of those group differences.
In this event, what if the behavioural scores are influenced by the group differences? For example, Grp 1 = healthy controls, Grp 2= patients with Parkinson's and the behavioural scores = motor task reaction time. I have conducted tests showing that: a) using TBSS, Grp 2 shows lower FA than Grp 1 in particular areas of the brain and b) t-test shows difference in behavioural measures (RT) between the groups, Grp 2 > Grp 1.
Given that I have established these two premises, I would now like to identify using TBSS, which areas of the brain would FA be significantly correlated with RT, across groups. I'm not sure if controlling for group differences would be ideal, given that this is directly related to the behavioural measure itself.
Thanks in advance for your advice!
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