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.
To clarify - I was looking for a simple government-refresher book to brush up for the Foreign Service Exam. I was not looking for a detailed explanation about the inner-workings of the Federal government.
It was exactly as I expected, and I got it for a good value. So while not terribly interesting reading, I found it to be an excellent, simple refresher.