Dear Laura,
I doubt whether you can simple average regression coefficients (beta maps) as obtained on the first level over neighbouring voxels (i.e. smoothing), and then take them to the 2nd level. 1st level beta maps might be differentially affected by non-random patterns in voxel-to-voxel noise during GLM estimation. But others might have different opinions.
Why not simply smooth at 10mm at 1st level and look at the consequences at 2nd level? That would assure many reviewers, to take a practical approach ;-)
Cheers,
Bas
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Dr. S.F.W. Neggers
Division of Brain Research
Rudolf Magnus Institute for Neuroscience
Utrecht University Medical Center
Visiting : Heidelberglaan 100, 3584 CX Utrecht
Room B.01.1.03
Mail : Huispost B01.206, P.O. Box 85500
3508 GA Utrecht, the Netherlands
Tel : +31 (0)88 7559609
Fax : +31 (0)88 7555443
E-mail : [log in to unmask]<mailto:[log in to unmask]>
Web : http://www.neuromri.nl/people/bas-neggers
: http://www.brainsciencetools.com (CEO)
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________________________________
From: SPM (Statistical Parametric Mapping) [[log in to unmask]] on behalf of Laura M. Tully [[log in to unmask]]
Sent: Thursday, April 26, 2012 12:56 AM
To: [log in to unmask]
Subject: [SPM] smooth at group level?
Hi SPMers,
Could someone tell me if it is possible to smooth at the group level in SPM8? I have data that is smoothed at 8mm in preprocessing, but I would like to look at between group effects in the LPFC at 10mm - is this possible?
thanks!
Laura
--
Laura Tully
Social Neuroscience & Psychopathology
Harvard University
840 William James Hall
33 Kirkland St
Cambridge, MA 02138
[log in to unmask]<mailto:[log in to unmask]>
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