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On Fri, Jul 5, 2013 at 12:24 PM, Sevel,Landrew S <[log in to unmask]>wrote: > SPM, > > If all contrasts entered into a 2nd level model have been produced with > the Replicate&Scale option, is it still necessary to keep the variance > setting in the 2nd level design specification set to 'unequal'? > It depends on whether you think the variance of each subject is the same or not. > > Worded differently, will contrast images created with the > Replicate&Scale option be put in the same scale for all participants or is > the scale independently determined by the sessions averaged and scaled on a > participant by participant basis? > The replicate & scale option is different than the variance issue. The scale issue makes sure that if subjects have different number of runs, then their contrasts will be the same if the response is the same in the runs that subjects do have. The variance question asks whether or not the subjects have the same variance (within-subject) or the groups have the same variance (between-groups). Hope this helps. > > Best, > > Drew >