Hello SPMers-
I need some advice regarding a problem I have encountered with
interpretation of a SVC analysis: A SVC analysis of a first level
interaction yielded cluster-level results of corrected p=0.002, k=285,
uncorrected p=0.005 with a 12 x 12 x 12 search volume. In the parameters
listed at the bottom of the SPM results page, the search volume was listed
as: S=1728 mm^3 = 216 voxels = 0.4 resels. How is it that the cluster
level results list a k value (285) that exceeds the search volume voxels
(216)? I thought the k value was the number of voxels exceeding the
threshold within the specified search volume and therefore could not exceed
the search volume in size. (I found that I used a search volume which is
specifically recommended against
in http://www.mrc-cbu.cam.ac.uk/Imaging/vol_corr.html, but I did not see
how this would result in the discrepancy between the cluster-level results
k value and the search volume). Can someone explain?
With thanks,
Brandall Y. Suyenobu, Ph.D.
Staff Research Associate
Brain Imaging Group
UCLA/CURE Neuroenteric Disease Program
Veterans Administration Greater Los Angeles Healthcare System
11301 Wilshire Boulevard
Building 115, Room 223
Los Angeles, California 90073
Tel: (310) 478-3711 ext. 40580
Fax: (310) 794-2864
http://www.med.ucla.edu/Cure
http://ibs.med.ucla.edu
http://mindbody.med.ucla.edu
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