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Firstly, I confess to a little ignorance for the rationale for modeling the block effect but assume this is equivalent to the "DC" or offset in the GLM, i.e. the y intercept (?). With that in mind, I have been attempting to replicate an SPM2 design in SPM5 for a two-group VBM analysis. In SPM2 I used the "compare populations 1-scan per subject" with ANCOVA. In SPM5 I have tried using both "independent t-test" and "full factorial" models, but in both cases, there is no modeled block effect. However, the df in both SPM2 and SPM5 designs is the same! (see attached) Is there an explantation for i) the absence of a modeleed block effect in SPM5; ii) the df being the same in SPM2 and SPM5 designs, where one (putatively) should have one df less (SPM2). Regards - MFG