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.
I loved a great deal about this series. The zombies are so very different, not so much of the bite, tear, eat. I loved the early Anna story. But by book 9 the wordiness was becoming less enjoyable. Still, as a post apocalyptic view it was different to the norm.