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 have been following the work of this book's author for 2 years and can say with no doubts that he is one of the most skilled guys related to QA Automation in terms of how to design properly an automation framework with tests and write clean and effective code. The book is oriented to people who want to go deeper into automation testing and start thinking and acting more as a Software Engineer in Testing, but not as a regular tester who is just producing big amounts of tests via code duplication and without any optimisation. Prior knowledge in OOP using C# or Java is required for the examples shown.