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.
What an amazing 4th book in this series and it keeps getting better. I love the way these authors put some angst in their stories. Luke and Scott's story was a sad one to start with and I felt for Scott at times. I would highly recommend this series to everyone.