Amazon calculates a product's star ratings based on a machine learned model instead of a raw data average. The model takes into account factors including the age of a rating, whether the ratings are from verified purchasers and factors that establish reviewer trustworthiness.
The book doesn't seem to have quite practical solutions. At each problem, the author asks to rely on god, tell him our problems and he will take care of it. Well believing in god is good, it might help people relax and think straight but even non believers think straight and are winners. So for me, this book is not quite practical.