Amazon calculates a product’s star ratings using a machine learned model instead of a raw data average. The machine learned model takes into account factors including: the age of a review, helpfulness votes by customers and whether the reviews are from verified purchases.
This book is useful in that it explores the "old" ways of praying and challenges the modern evangelical method of "quiet time", particularly our shopping list requests from God. Useful, also were the practical exemplars at the back of the book. This book was challenging as it quotes and explores the writing of "older" theologians.