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'm an indies/self-publishing author and I've also got Craig's first non-fiction book. That was good. This was amazing! Because of this book I now have a proper game plan and hope one day to meet the man and shake his hand while thanking him. The highlight of the book is the bullet points that come with each chapter, for me they are the actions needed. If you are struggling like me, get it now!