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.
My first pair of Birkenstock’s. Comfy after a couple of weeks, I followed the advice of wearing with socks for short periods of time to start with and now really enjoying them. They arrived just a few days after ordering and appear to be true to size and good quality.