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.
Awesome read! Truly well described techniques and tips to turn a small business into a larger corporation! Very smart and efficient ways to do so effectively described in this book. Loved the simplicity of putting through seemingly complex strategies of building a mega corporation.