Hey Doug, Great, but besides the unbalanced numbers in each cohort, the fact that we have a cross sectional analysis instead of a longitudinal one doesn't matter right? Would it be correct to say that we still apply the same group analysis described in the wiki?
Thanks, Panos ________________________________________ From: freesurfer-boun...@nmr.mgh.harvard.edu [freesurfer-boun...@nmr.mgh.harvard.edu] on behalf of Douglas N Greve [gr...@nmr.mgh.harvard.edu] Sent: Friday, May 31, 2013 11:59 AM To: freesurfer@nmr.mgh.harvard.edu Subject: Re: [Freesurfer] Group Analysis Hi Panos, are you asking whether theunbalanced design will leadto one slope being different than another just because the numbers are different? That is not a problem. You can simply follow the instructions on the wiki. doug On 05/31/2013 11:26 AM, Fotiadis, Panagiotis wrote: > Hey Doug, > > Sorry for the overwhelming amount of questions. I wanted to confirm > something. Suppose you want to do group analysis between two groups say a > healthy cohort vs a diseased cohort. Each cohort has ~40 and ~30 subjects > each (different people), and you want to compare how for instance the > cortical thickness decreases over age in the one group versus the other. Do > you still set the contrast vector as [0 0 1 -1] ([intercept 1 intercept 2 > slope 1 slope 2]) and follow the analysis described in > https://surfer.nmr.mgh.harvard.edu/fswiki/FsTutorial/GroupAnalysis or do you > go on a different way since there are different subjects instead of one with > 40 (or 30) different longitudinal data for each cohort? Don't we need to > correct the age slopes for the fact that we have 40 (and 30) different > subjects in each cohort? > > Thanks, > Panos > _______________________________________________ > 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 _______________________________________________ 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.
