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>
> Hello,
>
> I recently ran a vertex wise analysis on two different projects the first
> had three groups with three co-variates that looked at if group membership
> was associated with brain volume. The second project had two groups with
> three co-variates looking at psychiatric x BMI interaction effect on brain
> volume. I'm interested in running ROI analyses in matlab to ensure the same
> matrices were used.
>
> To run the ROI analyses I'm going to important the design matrix from the
> vertex wise analysis and use the fast_glmfit and fast_fratio commands as
> shown below:
> X = load('Xg.dat');
> C = load('C.dat');
> y = load('ROI.dat'); text file containing participant ROI values from the
> DKT atlas.
> [beta rvar] = fast_glmfit(y,X);
> [F pvalues] = fast_fratio(beta,X,rvar,C
>
> My first question is the beta values that are calculated from fast_glmfit
> are unstandardized is there anyway way to have it compute standardized
> values?
>
> I think this is how you would compute that
> betastddev = sqrt(rvar*diag(inv(X'*X)));
> betastandard = beta./betastddev;
>
When I try running this in Matlab I get the Error using *** incorrect
dimensions for matrix multiplication message.> > My second question is when I ran the ROI analyses looking at the diagnosis > x BMI interaction effect it outputs an array of beta values for each > regressor. In addition to each groups beta value (for BMI) I'm interested > in the beta value of the interaction (ie diagnosis x BMI). I was wondering > how do i go about obtaining this? Would I have to create a new matrix with > the interaction term included in it? > > If so would the analysis essentially be one group with the diagnosis x BMI > interaction term plus the three co-variates? > > If you are using an FSGD file and have used DODS, then you can create an > interaction contrast. Send me your fsgd file if you want further help > Yes I was using DODS approach for this analysis, I've attached my FSGD file to this email. > > _______________________________________________ > 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
BMI.FSGD
Description: Binary data
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