When I run "lrm" from the Design package, I get a warning about
contrasts when I include an ordinal variable:
Warning message:
Variable ordfac is an ordered factor.
You should set
options(contrasts=c("contr.treatment","contr.treatment"))
or Design will not work properly. in: Design(eval(m, sys.parent()))
I don't get this message if I use glm with family=binomial. It produces
linear and quadratic contrasts.
If it's improper to do this for an ordinal variable, why does glm not
balk?
Rick B.
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