How imbd ranks movies?

The formula for calculating the Top Rated 250 Titles gives a true Bayesian estimate:

$WR=frac{nu }{nu +m}R+frac{m}{nu +m}C$

• where:*

$R$ = average for the movie (mean) = (Rating)

$nu$ = number of votes for the movie = (votes)

$m$ = minimum votes required to be listed in the Top 250 (currently 1500)

$C$ = the mean vote across the whole report (currently 6.9)

• for the Top 250, only votes from regular voters are considered.* (source)

Now that’s something unexpected! Going further than the simple arithmetic mean is something exciting, right?

The formula is the well-known decomposition of the posterior mean -distributed a priori as normal- compromising the prior guess ($C$) and the data ($R$) weighted by the sample ($nu$) and the pretend-to-be initial sample ($m$) under the conjugate prior setting.