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 really liked this supplement. Even though I had a different textbook than the one the supplement is based on, it still contained and explained the concepts that were taught to me in class and I had a hard time understanding. The book contains explanations as well as exercises to help you understand the difficulties that everyone encounters in a T&E class. I found this book helpful and I’d recommend it to anyone looking for a good supplement.