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.
I learned space plasma physics from Dr. Parks many years ago based on his popular text book, "Physics of Space Plasmas". In this more traditional book, the author emphasized learning fundamentals of electromagnetism and plasmic physic and then applying this knowledge to describe and understand space phenomena.
In his new book, Dr. Parks uses the opposite approach by first showing real world data from satellite observations of space plasmas. He then describes the plasma physics fundamentals needed to explain the observations.
Personally I like this "data-driven approach" much better. It keeps readers focused on the subject and learning is more fun and rewarding with a clear purpose. This book properly emphasizes particle kinetic and collision-less plasma effects and would be an excellent complement to many traditional space plasma text books.