yes, just note that they are somewhat different hypothoses that you are testing as noted by Mike in the past. If you use average surface area/thickness you are testing the hypothesis that part of the brain is not changing/different relative to the average. If you control for TIV (or the 2/3 root of it I guess for surface area) you are looking for any change while removing head size as a nuisance variable. I think Mike's is probably the more interesting approach, but they are somewhat distinct.

cheers Bruce

On Mon, 4 Jul 2016, Arkadiy Maksimovskiy wrote:

Hi Clara, Yes- my apologies. I misunderstood your initial analyses description. Sounds right to me as well.

• Arkadiy