On Aug 29, 2010, at 3:13 PM, moleps wrote:
glm(A~B+C+D+E+F,family = binomial(link =
"logit"),data=tre,na.action=na.omit)
Error in `contrasts<-`(`*tmp*`, value = "contr.treatment") :
contrasts can be applied only to factors with 2 or more levels
however,
glm(A~B+C+D+E,family = binomial(link =
"logit"),data=tre,na.action=na.omit)
runs fine
glm(A~B+C+D+F,family = binomial(link =
"logit"),data=tre,na.action=na.omit)
runs fine
glm(A~E+F,family = binomial(link =
"logit"),data=tre,na.action=na.omit)
Error in `contrasts<-`(`*tmp*`, value = "contr.treatment") :
contrasts can be applied only to factors with 2 or more levels
Why is this? Could it be due to collinearity between the two?
Perhaps, at least to the extent that the term "collinearity" is an
appropriate term for factor interactions. The obvious question at this
point is: What does:
with( tre, table(E,F) ) # show?
--
David Winsemius, MD
West Hartford, CT
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