Movie ratings the Bayesian way

Many Web sites that let visitors rate a product, such as a movie or car, calculate the simple mean statistic as an indicator of the product's goodness. Internet Movie Database, owned by Amazon.com, favors Thomas Bayes' approach, otherwise known as the Bayesian Theorem. The 18th-century probability theorist, for whom the formula is named, believed they should use their prior knowledge when encountering new situations, reports Carl Bialik, the "numbers guy" at The Wall Street Journal. The rating is adjusted based on the number of ratings and not just the average of the ratings per se.