Arithmetic Mean / Average Rating

  • 1
  • Problem
  • Updated 4 years ago
  • Not a Problem
I would like to receive some explaination for the vote that appears on my movie page. The real arithmetic mean comes out to be 5.6. But the shown rating is always 4.8. I understand your policy of the weighted average, but can't really undersant how is it possible that the difference is so big (from 5.6 to 4.8 !! ) and why the rating does not change even if there was a growth in the voters. Would you be so kind to check the rating of the movie 'La foresta di ghiaccio' in case there was an issue? thank you
Photo of Claudio Noce

Claudio Noce

  • 1 Post
  • 0 Reply Likes

Posted 4 years ago

  • 1
Photo of Michelle

Michelle, Official Rep

  • 12714 Posts
  • 9619 Reply Likes
Hi Claudio -

IMDb does not use the arithmetic mean when calculating the ratings, although the raw mean and median are shown under the detailed vote breakdown graph on the ratings pages. Instead we use a weighted average scheme. This explains why there's often a discrepancy between the user rating displayed on a film's title page and the arithmetic mean of all the votes cast for that film.

For more details about IMDb weighted ratings, see here: http://www.imdb.com/help/show_leaf?voteaverage
(Edited)