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.
an utter waste of money. It costs as much as the book, but every time I have to go through the rigamaroll of f***ing apple store and put in my credit card just to open it in kindle. Also there aren't any page numbers, so whenever I have to look at it in class it's basically impossible. It would've been so easy to include page numbers, as that's how textbooks usually work....so frustrating I wish I could return it.