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 was hoping it would elaborate on the more interesting aspects of psychology which was why I started reading it really didn't teach me anything new. It really is just an introduction to psychology so if you dont know much about tye topic at all I highly recommend this book. For me personally though, it was average.