Hi Doug, Thank you for your advice. Would you also have any advice on what would be the correct process to follow if volume based smoothing at subject level(4mm) and surface based smoothing at group level(4mm) are applied? Many thanks, Mariam.
On 31 Mar 2014, at 16:36, Douglas N Greve <gr...@nmr.mgh.harvard.edu> wrote: > > On 03/31/2014 10:05 AM, Mariam Sood wrote: >> Hi Doug, >> >> I have a few queries regarding FWHM used in multiple comparisons correction >> program mri_glmfit-sim >> >> My data at present is analysed in FSL & Freesurfer following the procedure >> in the link >> http://surfer.nmr.mgh.harvard.edu/fswiki/FsTutorial/FslFeatFreeSurfer. No >> volume based smoothing at single subject level (in FSL) is done at the >> moment, and a 4 mm surface level smoothing was applied during mris_preproc >> stage. >> >> 1. I have noticed that mri_glmfit computed a FWHM of 8.578114 using >> residuals. How exactly is this value computed? > It is based on the correlation coefficient of the residuals of adjacent > vertices. >> 2. I understand that the cached simulation used in mri_glmfit-sim is >> selected based on the above computed smoothness value. Is this fine, or >> should I override? If I also smooth the data at the single subject level on >> the volume (in FSL), can I still follow the above process? > Do you mean over-ride because you smoothed at 4 but get 8.5? No, you > would use the 8.5. If you smoothed in the volume, depending on how much, > it is probably ok to continue the process (though technically not correct) > doug >> >> Many thanks, >> Mariam. >> >> >> >> >> >> >> >> >> >> _______________________________________________ >> Freesurfer mailing list >> Freesurfer@nmr.mgh.harvard.edu >> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer >> >> > > -- > 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: https://gate.nmr.mgh.harvard.edu/filedrop2 > www.nmr.mgh.harvard.edu/facility/filedrop/index.html > Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/ > > _______________________________________________ > 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. > _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
