Your problem seems to be exactly the problem I've been having for the past week. So glad to find this thread. However, when I follow the syntax you used to get around the issue, I still didn't get the output to work in the way yours did. I don't believe my factors are truly nested however (nor your factors: if A, B, C, and D occur in both levels 1 and 2, the effects would be crossed).
I have a model with the variable condition, and the variable patient (indicating whether the subject is a patient or control) with repeated measures per subject, and the following is the model I had: MLsd = lmer(H.y.~patient*stance*cond + (1|subj), data=H) I want to be able to look at the same contrast set up you were interested in, and compare patient to control at every level of the variable condition (cond). *When I tried using the syntax you used with my model: lmer(H.y.~patient*stance*cond+(cond/patient) + (1|subj), data=H), I got this result, which seems to be using condition 1 as a part of the baseline. Any idea how to change that?* Fixed effects: Estimate Std. Error t value (Intercept) 0.552594 0.012774 43.26 patient1 -0.005951 0.016989 -0.35 stance2 -0.009010 0.014577 -0.62 cond2 -0.023666 0.007028 -3.37 cond3 -0.015469 0.006948 -2.23 patient1:stance2 0.027988 0.019472 1.44 patient1:cond2 0.015981 0.009977 1.60 patient1:cond3 0.014622 0.009905 1.48 Best, Rachel (M.S. candidate frantically working to finish her master's project in the coming week or so) -- View this message in context: http://r.789695.n4.nabble.com/Contrasts-for-2x4-interaction-in-mixed-effects-model-tp4642536p4642710.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.