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.
Reviewed in the United States on December 13, 2019
WARNING: This is not written by the speculative fiction author William Gibson, despite the incorrect "Follow the Author" link currently on the page (I've already informed Amazon of the error). It was written in 1860, by a minister who died in 1867.