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.
Lonely Planet have such a great series of travel guides. I always pick one of these up before I start planning my trip and then take it with me when I go away. The information they contain is invaluable, and the Thailand guide book is no exception. So much detailed information and recommendations. Highly recommend to anyone who is planning a trip to Thailand.