where:
- W is the weighted rating;
- R is the mean rating for the movie, from 1 to 10;
- v is the number of votes for the movie;
- m is the minimum votes required to be listed in the Top 250 (25,000 as of 2013)
- C is the mean vote across the whole report (7.0 as of 2013).
The variable W in this formula is equivalent to a Bayesian posterior mean (see Bayesian statistics).[citation needed]
The IMDb also has a Bottom 100 feature which is assembled through a similar process although only 10,000 votes must be received to qualify for the list.[12]
The Top 250 list comprises a wide range of feature films, including major releases, cult films, independent films, critically acclaimed films, silent films, and non-English-language films. Documentaries, short films and TV episodes are not currently included.
Since 2015, there has been a Top 250 list devoted to ranking television shows.[13]