This function is needed to re-fit the models for Type III SS. If you have a model with an
interactive term (e.g. y ~ a + b + a:b), when you try to refit without one of the lower-order
terms (e.g. y ~ a + a:b) lm() will add it back in. This function uses a fitting function
that operates underneath lm() to circumvent this behavior. (It is very similar to drop1().)
drop_term(fit, term)An object of the class lm.
The model to update.
The term to drop from the model.