Hi Luis,
the extent threshold value specifies the minimum number of voxels a
cluster has to meet in order to be displayed. If set to 0, all voxels
meeting the voxel threshold criterion will be displayed (default). If
you set it to, say, 10 in an fMRI study, cluster not reaching 10 voxels
will be hidden. If you search for "cluster extent" and "cluster
corrected" thresholds in the list archives at
https://www.jiscmail.ac.uk/cgi-bin/webadmin?S1=spm , you will find some
hints as to which values may be considered reasonable to some :)
Cheers
Marko
Luis Casado Aranda wrote:
> Hi everyone,
>
> I'm starting with the use of SPM and I have one question about the contrast step. What is the 'extent threshold voxels' and how to change the value of 0 in SPM8?
>
> Thank you very much in advance
>
>
--
____________________________________________________
PD Dr. med. Marko Wilke
Facharzt für Kinder- und Jugendmedizin
Leiter, Experimentelle Pädiatrische Neurobildgebung
Universitäts-Kinderklinik
Abt. III (Neuropädiatrie)
Marko Wilke, MD, PhD
Pediatrician
Head, Experimental Pediatric Neuroimaging
University Children's Hospital
Dept. III (Pediatric Neurology)
Hoppe-Seyler-Str. 1
D - 72076 Tübingen, Germany
Tel. +49 7071 29-83416
Fax +49 7071 29-5473
[log in to unmask]
http://www.medizin.uni-tuebingen.de/kinder/epn/
____________________________________________________
|