Amazon calculates a product’s star ratings using a machine learned model instead of a raw data average. The machine learned model takes into account factors including: the age of a review, helpfulness votes by customers and whether the reviews are from verified purchases.
At last; a storyline very different to so many other books of this genre. I enjoyed learning about the vastly different characters, and there were a number of plots bubbling away in the background, keeping the interest. But they all came together in the end, making for one of Nash's better works. Keep 'em coming!