Hi experts, I have a follow up question: In case I wanted to add another covariate in contrast matrix e.g. in addition to age and gender if I want to add BMI as another covariate in calculating correlation between volume and LGI (as mentioned in previous email), could you please confirm if following contrast matrix is correct:
*0 0 0 0 0 0 1* for FSGD: GroupDescriptorFile 1 Class Male Class Female Variables Age BMI Input zerek1 Male 21 17 Input zerek2 Male 25 19 etc. If that's the correct matrix, could you please briefly explain how this matrix explains the effect of age, sex and BMI i.e. how does each zero and 1 explain the correlation between volume and LGI and removes the effect of age, sex and BMI? Thanks. On Tue, May 16, 2017 at 8:31 AM, Douglas Greve <gr...@nmr.mgh.harvard.edu> wrote: > The 2nd is the correct matrix > > On 5/15/17 12:36 PM, Sahil Bajaj wrote: > > Hi everyone, > > From FreeSurfer manual and discussion forum, I found that volume and LGI > can be correlated using mri_glmfit command with -pvr flag. > > For that, my fsgd file has age, gender as covariates and the file is as > following: > > GroupDescriptorFile 1 > > Class Male > > Class Female > > Variables Age > > Input zerek1 Male 21 > > Input zerek2 Male 25 > > etc. > > My concern is: > > To run mri_glmfit command, I am not sure how to define my contrast matrix > if I am interested in removing the effect of age and sex. > > 1st option I tried is: 0 0.5 0.5 0 1 > > Here, I think first 0 regresses out age, 0.5 0.5 should be averaging over > males and females and last 0 1 correlates between volume and LGI. But this > looks like it is not giving me correct correlations maps, although there is > no error. > > 2nd option I tried is: 0 0 0 0 1 > > This looks like its working and maps look correct to me but I want to > make sure this is the correct contrast matrix and I am not sure how this > matrix is regressing out age and gender or 1st option is correct contrast > matrix? > > Thank you so much ! > > Best, > > Sahil > > > _______________________________________________ > Freesurfer mailing > listfreesur...@nmr.mgh.harvard.eduhttps://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. > >
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