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.
Great idea Kristy! I have also seen my mother sometimes struggle to find a babysitter for my younger sister. I would offer except that my sister is only 2 years younger than me so my mum won't let me babysit either.