More golf putting, leading to a discussion of how prior information can be important for an out-of-sample prediction or causal inference problem, even if it’s not needed to fit existing data

Steve Stigler writes: I saw a piece on your blog about putting. It suggests to me that you do not play golf, or you would not think this was a model. Length is much more important than you indicate. I attach an old piece by a friend that is indeed the work of a golfer! …