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.
The content review is excellent for MCAT prep. However, I recommend buying the paperback a) it's cheaper and b) the formatting is much better on a paper back version of this book. If ONLY they made continuous scrolling available for this book on Kindle the problem would be fixed since the swipe version cuts through important figures/tables. The formatting is distracting but the content otherwise is amazing and I love Kaplan for it!!