Amazon does a similar thing to seller ratings: https://images-na.ssl-images-amazon.com/images/G/01/sellerfeedback/time-weighted-graph-2._V389181558_.png https:/

Amazon does a similar thing to seller ratings: https://images-na.ssl-images-amazon.com/images/G/01/sellerfeedback/time-weighted-graph-2._V389181558_.png https://images-na.ssl-images-amazon.com/images/G/01/sellerfe... . Ratings have an initial slow impact (this is more to do with getting the goods to the user and allowing the returns process to run it's course) then the feedback has a 100% affect that tails off over a year or two. A similar approach could be used by google.