Yes, you need to correct over both hemispheres. The way we do this in FreeSurfer is to first correct over the hemispheres independently. This gives a cluserwise p-value for each cluster. We then bonferroni correct across hemispheres, which basically means multiplying the clusterwise p-value by 2. This is what happens when you run mri_glmfit-sim with the --2space flag (or set the clusterwise p-value threshold to .025 when correcting at the .05 level). Did you use either of those techniques?
doug On 01/27/2014 03:36 PM, Cat Chong wrote: > Dear Experts, > I was wondering if you could possibly help me with a reviewer-related > question: > We conducted a between-group-analysis estimating the interaction > between cortical thickness and age. > In summary, we wanted to investigate whether the interaction between > cortical thickness and age is stronger for one group relative to > another (using a DODS design). > We cluster-corrected our results using a Monte Carlo cluster > correction of p<0.01 and attained significant group differences for > several areas over the left and right hemisphere. > One of the reviewer commented that although group differences were > estimated for each hemisphere separately, they ought to have been > cluster-corrected for both hemispheres. > Would you be able to tell me whether or not cluster-correcting for > both hemispheres is a necessity, or help me understand the possible > implications of not having cluster-corrected for both hemispheres? > Very Best Regards, > Catherine > > > _______________________________________________ > Freesurfer mailing list > Freesurfer@nmr.mgh.harvard.edu > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer -- Douglas N. Greve, Ph.D. MGH-NMR Center gr...@nmr.mgh.harvard.edu Phone Number: 617-724-2358 Fax: 617-726-7422 Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting FileDrop: https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/facility/filedrop/index.html Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/ _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Partners Compliance HelpLine at http://www.partners.org/complianceline . If the e-mail was sent to you in error but does not contain patient information, please contact the sender and properly dispose of the e-mail.
