IMDB uses something like this. It's called a "weighted" rating system. In the IMDB version what happens is that you calculate the average of all ratings of all

IMDB uses something like this. It's called a "weighted" rating system. In the IMDB version what happens is that you calculate the average of all ratings of all items, and then push an item's rating towards the average. The fewer ratings it has the more it's pushed. See http://www.imdb.com/help/show_leaf?votes http://www.imdb.com/help/show_leaf?votes for details.