Thanks Dr. I did read the help page but maybe I just don't understand enough about contrasts to take what I need from it. It says:
"If value supplies more than how.many contrasts, the first how.many are used. If too few are supplied, a suitable contrast matrix is created by extending value after ensuring its columns are contrasts (orthogonal to the constant term) and not collinear." I suppose what this means is that if the matrix is not extended then there is some type of problem with orthogonality? Perhaps my real question should be, why is a contrast matrix with only one column not suitable. Maybe I should read the book you are referring to. Can you provide a reference? Thanks! -- View this message in context: http://r.789695.n4.nabble.com/What-is-the-effect-of-how-many-in-the-contrast-function-tp4685294p4685300.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.
