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.
Essential book for Blue Mountains bushwalkers - a whole host of excellent hikes to get you started in this beautiful region of NSW, Australia just outside of Sydney. Highly recommended! Only criticism is I think the pictures really don't do the hikes justice, I can only assume this is intentional so as not to spoil the 'wow' of experiencing the views for the first time yourself, so don't be put off!!