Dear DCM experts
We have used DCM post-hoc on a group of patients and a group of controls, and tested the full model with spm_dcm_fmri_check. While the control group shows a good percentage of variance explained by the full model, for about 40% of the patients the variance explained by the full model is < 10%. This did not change by increasing the size of the VOIs, or by choosing a stronger peak. For these participants the variance explained in specific VOIs is low even for VOIs with >30 active voxels.
1. Do you have any suggestion for what we can do to avoid excluding these participants?
2. In principle - is the variance explained by the full model always greater than that explained by any reduced model?
Thanks a lot
Tali Bitan
University of Haifa
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