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