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
Try using the version 6 mri_glmfit. It will produce identical results and it will also create the pcc.mgh output
On 05/12/2017 12:02 PM, Clint Johns wrote:
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.htm... 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 mailto:johns@haskins.yale.edu
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