There is a mixed effects e-mail list you might want to join for more in depth discussion of these topics - you can subscribe here https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models.
In general the format for crossed effects would be lmer(y~f1+f2+(1|r1)+(1|r2)) where f1, f2 are fixed effects and r1, r2 are random. I believe that the random lines correspond to those in SAS as below random int/subject=r1; (1|r1) for random varying intercept with each r1 random f1/subject=r1; (f1|r1) for random varying slope with each r1 However, in your case, I suspect that the model might not run because crossed random effects generally take time and with 3 way interactions that's probably too much for R. Either way, you can check that by building your model up slowly and seeing if it runs for the simpler case. Let me know how far you get, Paul -- View this message in context: http://r.789695.n4.nabble.com/A-question-about-conducting-crossed-random-effects-in-R-tp2278443p2280578.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.