It does not discredit your results. This is not unexpected behavior. As you change cluster forming thresholds, the clusters will change sizes, but the null distribution will also change in complicated ways. The end result is that it is not easy to predict the effect on the number and sig of your clusters.
> Dear Douglas, > > I have run GLM group analyses with Freesurfer tools according DODS model, > with six classes ((Male,Female) ; (Control,Left,Right)) and one age variable : > > Class MaleControl > Class MaleLeft > Class MaleRight > Class FemaleControl > Class FemaleLeft > Class FemaleRight > Variables Age > > I wanted to test Control > Left and on CBF maps. I defined with help of the > tutorial contrats for that : > > control-left.intercept.mtx : 0.5 -0.5 0 0.5 -0.5 0 0 0 0 0 0 0 > > I have run mri_glmfit-sim to correct for multiple comparisons with three > different cluster-forming threshold : 4, 2 and 1.3. What surprising me is > that I obtained significant cluster for threshold of 4 and larger significant > cluster for threshold of 1.3, but nothing significant with threshold at 2... > > How is it possible and does this discredit my significant results ? > > Please find attached my results files. > > Best regards, > > ------------------------------------- > Matthieu Vanhoutte, MSc > Research Engineer - Department of Neuroradiology > Regional University Hospital, Lille, France _______________________________________________ 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.
