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.
The scales work well, they are not that accurate, e.g. weighing myself with and without about 400g of stuff in my pockets doesn't change the reading, but it's near enough to see how your weight is going
The scale arrived exactly on time, if not a bit earlier. I like the sleek look and size of the product, and it is very simple to use. Just put it on a hard surface and step on it then you're good to go.