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.
All the calculations in this book are based an an important date key. Nowhere in the book could I find such a key or discussion of this critical date. I checked some calculations for star longitudes, and they seemed erratic, as if they were based on faulty calculation software. I am not sure how this book came to be published. I returned the book to Amazon for a refund.