On May 3, 2013, at 3:32 PM, Iuri Gavronski wrote: > Hi, > I would like to know the criteria by which R removes a factor in linear > models. For example, I have a four level factor, and R creates 3 dummies to > estimate coefficients. Which level is chosen? Can I chance it?
The default order is alphabetical. Lowest lexical sorted item is the reference level. Changing levels is possible: ?levels ?factor -- David Winsemius Alameda, CA, USA ______________________________________________ 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.
