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.
This book is in all ways sheer disappointment. Firstly, the editing: 1. the pages are not numbered (could you believe it?) 2. there are numerous pages on which the font size is intentionally and exaggeratedly increased (text which would comfortably fit in 1/8 page is spread over two pages). The purpose is to artificially increase the number of pages so that prospective buyers are tricked more easily. Secondly, the content: 1. the material is not well systematized, there is no hierarchy (the font size varies chaotically so the reader never knows whether the section they are reading is important or should be overlooked, it is very difficult to see where a chapter or subchapter begins/ends. 2. the main aspects and requirements for different tasks are not clearly explained; there is no clear structure given for any of the tasks, the students will not learn how to approach the task. 3. some vocabulary is given but this is overshadowed by the aspects mentioned above. In a nutshell, this book will confuse the learner (they will have to reorganise and complete the material themselves). As for tutors, it is pretty useless.