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.
My niece is 14 year old and she likes to study story books. I used to purchase Diary of a wimpi kid for her then i started searching for such a book series which is adventurous , intresting and with a moral too. And i found all those things in Drew Diaries.