Trying to use gam::step.gam to build a model. Don't understand why that function asks for a formula if the input model object already has an embedded formula (from when it was fit via gam::gam)
Why ask for the formula twice? When would I want to use different formulas between the two functions?
My review of help("gam") and help("step.gam") didn't uncover anything to explain why I'd use one formula when first fitting model with gam and another when feeding that model to step.gam.