Dear Peter, dear SPM-experts,
some time ago I posted a question about very low percentage of explained variance (0%) when checking my DCMs with spm_dcm_fmri_check.
(see https://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind1411&L=spm&F=&S=&X=4C60EE6C21C6F1C1B5&Y=eric.holst%40web.de&P=334445)
As this could be due to complexity of my DCMs I have reduced my basic model from 6 to 3 regions, but explained variance is still at 0%.
I have read about increasing the area of the VOIs (I am using a 6 mm sphere), but most of my VOIs already consist of 30+ voxels.
[Btw: I smoothed my data in preprocessing.]
Now I am wondering about the right way to proceed. What should I do now to improve my models?
Any help is appreciated and thanks in advance,
Eric Holst
Department of Neurology
Charité, Berlin, Germany
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