Hello everyone,
I have a variable with several categories and I want to convert this
into dummy variables and do logistic regression on it. I used
model.matrix to create dummy variables but it always picked the
smallest one as the reference. For example,
model.matrix(~.,data=as.data.frame(letters[1:5]))
will code 'a' as '0 0 0 0'. But I want to code another category as
reference, say 'b'. How to do it in R using model.matrix? Is there
other way to do it if model.matrix has no such functionality?
Thanks!
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