To calculate the overall star rating and percentage breakdown by star, we do not use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyses reviews to verify trustworthiness.
While the contents of the book is undoubtedly interesting, reading the book is extremely painfully stressful on the eyes. The font size is so tiny, you will need a magnifying lens to read, very disappointed with the tiny font size. I wish the publisher of the book had used larger font size.