Hi Jean, contr.treatment(4) shows what the default contrast matrix looks like for a factor with 4 levels. What function do I use to create a contrast matrix to compare each level with the global mean (four comparisons in total), and produce a table similar to `summary.lm`?
Thanks, Shaun On 26 June 2013 05:50, Adams, Jean <jvad...@usgs.gov> wrote: > Shaun, > > See the help on contrasts ... > ?contr.treatment > > Jean > > > On Tue, Jun 25, 2013 at 7:07 PM, Shaun Jackman <sjack...@gmail.com> wrote: >> >> Hi, >> >> I've used `lm` to create a linear model of a continuous variable >> against a factor variable with four levels using an example R data set >> (see below). By default, it uses a treatment contrast matrix that >> compares each level of the factor variable with the first reference >> level (three comparisons in total). I'd like to compare each level >> with the global mean (four comparisons in total), and produce a table >> similar to `summary.lm`. How do I go about this? >> >> ```r >> model <- lm(weight ~ Diet, ChickWeight) >> summary(model) >> ``` >> >> Thanks, >> Shaun >> >> ______________________________________________ >> 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. > > ______________________________________________ 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.