I think the problem may be that your data are "badly scaled" meaning that one column is much greater than another column. Try dividing the ICV by 1e6 and see if you get more similar results.
doug soft.join Huang wrote: > Doug, > > Thanks for your reply. > I recalculated the beta value and got the same results as the Matlab > does, but be different from the mri_glmfit's. I can not figure out > where the problem is. > Details following: > I use the command > mri_glmfit --table lh.volume.txt --fsgd volume.gender.fsgd > doss --C gender.diff.mtx --glmdir lh.vol.glmdir > to finish regression analysis. and got the beta value ( beta1 = > 1.9781e+03, beta2 = 2.0639e+03, beta3 = 110.9220, beta4 = 5.1964e-04 ) > from beta.mgh file. > Using X.mat file and the same dependent variable Y.mat as > mri_glmfit's, I got totally different results in Matlab( beta1 = > 5.19e+02, beta2 = 4.44e+02, beta3 = 90.32, beta4 = 0.0015 ). > I don't know how it happened... > > Hope for your reply. > The data I used are all in the attachment. > > Best Regrads, > > Lijie Huang > On Fri, Apr 29, 2011 at 9:45 PM, <gr...@nmr.mgh.harvard.edu > <mailto:gr...@nmr.mgh.harvard.edu>> wrote: > > Lijie, > > I don't know what the matlab regress() function does. mri_glmfit > is just > solving the GLM equation, which you can do easily in matlab: > > beta = inv(X'*X)*X'*y; > > try that and see if you get the same as mri_glmfit. > > doug > > > > Hi all, > > > > I'm working on a group analysis using mri_glmfit. > > In analysis directory, I got a X.mat file which containing the > matrix X ( > > size 50x4 ) used to regress analysis, also the beta value from > beta.mgh > > file. > > Strangely, I loaded the X.mat in Matlab and recalculated the > beta using > > function regress in matlab, but got a different result from that of > > mri_glmfit. > > I don't know where the problem is, is there any difference in > algorithm > > between mri_glmfit and matlab function regress( regress(Y,X) )? > or I made > > some mistakes during the procedure. > > The X.mat file and the dependent variable Y.mat are in the > attachment. > > > > Thanks in advance > > > > Lijie Huang > > _______________________________________________ > > Freesurfer mailing list > > Freesurfer@nmr.mgh.harvard.edu > <mailto: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. > > -- Douglas N. Greve, Ph.D. MGH-NMR Center gr...@nmr.mgh.harvard.edu Phone Number: 617-724-2358 Fax: 617-726-7422 Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting FileDrop: www.nmr.mgh.harvard.edu/facility/filedrop/index.html _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
