To calculate the overall star rating and percentage breakdown by star, we don’t 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.
Found the book for very helpful,Exhaustive content. Slight dislike would be it doesn't provide any structured approach or daily steps to follow to be successful in this art form .You have devise your own method following the content