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.
Great book with solid science, but did the author and publisher not notice the irony in their very earth *unfriendly* product, with its thick, glossy pages that contain vast amounts of four-color illustrations and illustrative text and background on every page? Lots of trees and energy used for every print run, I'm sure, which deters greatly from the message of this book. Someone didn't think this one through.