Hi Douglas, Thanks for your response. I just wanted to confirm how the FSGD and contrast files might look for the multicentre study. If I'm to create a separate class for each combination of diagnosis, sex, and center, would there then be 24 classes? (as there are 2 diagnoses (patient vs. control), 2 sex, and 6 centres). For instance: GroupDescriptorFile 1 Group control_Male_centre1 Group control_Female_centre1 Group control_Male_centre2 Group control_Female_centre2 Group control_Male_centre3 Group control_Female_centre3 Group control_Male_centre4 Group control_Female_centre4 Group control_Male_centre5 Group control_Female_centre5 Group control_Male_centre6 Group control_Female_centre6 Group patient_Male_centre1 Group patient_Female_centre1 Group patient_Male_centre2 Group patient_Female_centre2 ...
Then, my contrast between patients and controls would look like 1 1 1 1 1 1 1 1 1 1 1 1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 0 for a doss model, if I'm additionally controlling for age, or 24 zeros (instead of 1) for a dods model? Moreover, should I expect any issues with using such a high number of classes? Thanks again, Colleen _______________________________________________ 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.
