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.
Brilliant read! This book is quite similar to one of the previous books (Infinite Manifestations) in that both stress on the importance of continuing to be in the zero state and not regress back. Only the techniques differ. This book advocates the use of the 'It is done!' technique while the former adopts a moment-by-moment awareness approach. Loved it :)