> Though I am concerned about what Dr. Ashburner has just said about
> the sensitivity of DARTEL in longitudinal analysis, in our case this
> analysis did detect significant regions - and in the hypothesized
> direction - so we are satisfied with this method. Worth mentioning
> perhaps is that our sample is children and adolescents, whose brains
> change substantially over the 2 year period between our time1 and
> time2. Maybe it is not the same for adults or with images closer in
> time.
I may be wrong about the accuracy for longitudinal data. What I wrote
was my best guess, with a bit of the reasoning behind it. I would
expect the sensitivity using a longitudinal DARTEL approach to be
slightly higher than VBM using a paired t-test. There is probably still
some room for improving the model accuracy though.
All the best,
-John
--
John Ashburner <[log in to unmask]>
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