Using Freesurfer 5.3.0, we assessed correlations. between behavioral measures (e.g., working memory, IQ) and grey matter thickness in a single group of participants. We obtained some results - a significant correlation between measure X and cortical thickness in, say, IFG. We would like to include the Pearson's r or some other measure of the effect size. Newer versions of Freesurfer allow this (pcc.mgh), but we are not sure what to use. We have the contrast effect size file gamma.mgh, and the gamma values are "C*beta, where beta are the regression coefficients, so gamma is a type of regression coeff" (per Doug G. in this old thread: https://mail.nmr.mgh.harvard.edu/pipermail//freesurfer/2016-April/045135.html). So how do we use these values in a table? They're not Pearson's r, or Cohen's d, obviously. Do we just label the column "peak contrast effect size", naming the values after the gamma.mgh file?

Thanks! (We're very confused.)

clint

I remain...

Clinton L. Johns, Ph.D.
Research Scientist, Haskins Laboratories
300 George Street
New Haven CT 06511
speech: 203-865-6163 x240
fax: 203-865-8963
net: johns@haskins.yale.edu