I'm doing this only for learning purposes. I've no intentions of reversing the methods of IMDB.
I asked myself I owned IMDB or similar website. How would I compute the movie rating?
All I can think of is Arithmetic Mean
For a movie data provided below computation would be
(38591*10 + 27994*9 + 32732*8 + 17864*7 + 7361*6 + 2965*5 + 1562*4 + 1073*3 + 891*2 + 3401*1) / 134434 = 8.17055953
My rating 8.17055953 which is close to IMDB's Arithmetic Mean.
- Whats wrong with my score? Why is it not ideal (because IMDB didn't use it)?
- If you had to compute. How would you have done it? What factors you would consider?
I'm not asking about the ranking mechanism for the Top/Bottom listing (that is shown here : http://www.imdb.com/chart/top). This question is about how IMDb turns the arithmetic mean into the weighted mean. Take "Manos: The Hands of Fate" — Unweighted mean 2.1, weighted mean 1.5. (Or "The Godfather", another example of ballot stuffing.)