Dear list-members, I just switched to R, so here probably a newbie question, I couldn't find a answer for yet: Assume a design with three repeated measures factors (F1-F3), I tried to run the following: aov(rt ~ F1*F2*F3 + Error(subject / (F1*F2*F3))) Comparing the output from here and SPSS (General Linear Model -> Repeated measures) I found, that R does all calculations right for the main effects of F1-F3, but seems to do something different for the interactions: Whereas SPSS gets the F for an interaction by dividing the MS of the interaction term (e.g. F1*F2) by the corresponding MS of the interaction with subject (then F1*F2*subject), R just divides all interaction MS by the residual MS. Could somebody point out to me, what I'm doing wrong or how I can get aov to use the appropriate error terms also for the higher order interactions? Thanks for helping! -- View this message in context: http://www.nabble.com/aov-and-errors-used-for-interaction-effects-tp16395617p16395617.html Sent from the R help mailing list archive at Nabble.com.