If a and b are factor variables are there any differences between ~ a:b ~ b:a ~ a %in% b ~ b %in% a
playing with model.matrix doesn't show any differences in the resultant matrices, which is what I expect based on my understanding if what's being specified. I'm hoping that someone can clarify what (if any) the differences are. Thanks, Dan -- Daniel Lakeland [EMAIL PROTECTED] http://www.street-artists.org/~dlakelan ______________________________________________ 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.