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? Thanks, Iuri [[alternative HTML version deleted]]
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