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Hi Helmut, I agree with all of Philipp's and Alex's comments; one minor thing I'd mention... > ***If*** 1=yes and 2=satisfactory, and if there are no format problems, > then off the top of my head I can’t see much of a problem (as shocking > as it sounds). Knowing you, you will of course check for any systematic > differences between the two preprocessing pathways… and I hope the two > groups don’t correspond to patients versus controls etc. Maybe it would be worth including a covariate to indicate processing pathway? Rather like the suggestion here http://en.wikibooks.org/wiki/SPM-VBM#Data_from_different_scanners Then your results will be (correctly) less significant the more correlated the processing pathway indicator variable is to the effect of interest. Best, Ged