Hi Jose
usually we don't need multiple averages (or study specific ones), which simplifies things considerably. Is there a reason you think you need one? We intentially use the gray/white boundary for this reason, which is insensitive to any possible cortical atrophy.
cheers Bruce
On Mon, 18 Feb 2019, Laboratorio de Neurociencia Funcional wrote:
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Dear all,
I am planning to run separate regression analysis with cortical thickness in two very different populations (young and elderly subjects). Depending on results, it may happen that I am interested in comparing regression slopes between the two groups. My question is: should I build one average subject for each within-group regression analysis (one for young and another for elderly), and another different average subject merging all subjects of the two samples to compare regression slopes? Or I should preferably use only one average subjects with all subjects in all within and between regression analysis?
Many thanks in in advance.
Best regards, Jose