sorry for the delay ... You will definitely need to change the contrast values so that the positives and negatives both add to the same number (with opposite sign). It is a bit of a judgement call in terms of removing them entirely. With an unbalanced design, you cannot remove the fixed effect of that particular site, and reviewer might object to that. I would probably run it both with and without to see if it really makes a difference. You could also test the significance of the other site effects and, if they are not sig, then argue that the site effect is small.
On 4/16/18 12:58 PM, C.P.E. Rollins wrote: > Hi, > > I just wanted to ask again regarding my question below. > > I've noticed that 2 of the centres contribute a smaller number of > subjects and don't in fact have any female controls. Should I remove > these as classes (ie. take out control_Female_centre1 and > control_Female_centre2) and then change the subsequent contrast file to > look like: > 1 1 1 1 1 1 1 1 1 1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 0 > Or would this be a problem since now the number of classes that are > controls or patients are uneven (10 vs. 12)? > > Thanks again, > > 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.
