Amazon calculates a product’s star ratings based on a machine learned model instead of a raw data average. The model takes into account factors including the age of a rating, whether the ratings are from verified purchasers, and factors that establish reviewer trustworthiness.
I was unfamiliar with Headley's work before this, but now I'll be on the lookout. I know this won't be anything revolutionary, but I did highlight so many passages from it. It reminded me heavily of The Refrigerator Monologues, beautiful, heartbreaking, wrapped in myth.