Create a separate class for each combination of diagnosis, sex, and center, then create contrasts that average over center.
On 4/6/18 7:11 AM, C.P.E. Rollins wrote: > Dear Freesurfer Developers, > > I'd like to do a standard CT analysis (patients vs. controls, covaried > for age and sex) on data from a multi-centre study and I'm wondering how > I should construct my FSGD file to code centre as a dummy variable. > Currently, my FSGD looks something like this: > GroupDescriptorFile 1 > Group Control_Male > Group Control_Female > Group Patient_Male > Group Patient_Female > Variables Age > Input subj001-002 Patient_Male 32 > Input subj001-003 Patient_Male 19 > Input subj001-040 Patient_Female 28 > ... > To include centre as dummy variable, would I add an additional column > for each centre and enter either a 1 or a 0 depending on whether that > scan is from that centre? For instance, there were 6 centres (scans for > patients and controls collected at each) in the study, so centre as a > dummy variable might look something like this (columns added on after > age)? > 0 0 1 0 0 0 > 0 0 0 1 0 0 > 1 0 0 0 0 0 > Moreover, would this be the best way to control for centre? > > Many thanks, > Colleen > > _______________________________________________ > 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.
