Geek Answers Handbook

How will you rate an IMDB movie?

I do this for educational purposes only. I have no intention of reversing IMDB methods.

I asked myself that I have an IMDB or similar site. How can I calculate a movie rating?

All I can imagine is a Weighted Average (this is nothing but an arithmetic mean)

For the movie data below will be

(38591 * 10 + 27994 * 9 + 32732 * 8 + 17864 * 7 + 7361 * 6 + 2965 * 5 + 1562 * 4 + 1073 * 3 + 891 * 2 + 3401 * 1) / 134434 = 8.17055953

alt text

My rating of 8.17055953 does not match the IMDB rating (= weighted average). So my conclusion is that I missed something, or my score is not a perfect estimate. I may have been missing everything.

  • What happened to my account? Why is this not perfect?
  • If you needed to calculate. How would you do that?
+4
source share
2 answers

Not quite off topic, but useful for you:

How ranking is calculated.

hope that helps

PS this is confirmed on this page:

IMDB chart

+7
source

First: your calculation (which is un average or just average) has a typo: you have 19562 '4' ratings, but you must have 1562 . Fixing this gives ~ 8.17, which is rounded to the same value as the average value of IMDB arithmetic.

Then, if you want a weighted average, you need to weigh something! So, for example, if users have a “reputation” or similar (at least the duration of the time registration), you can use this as a multiplier for the weight of your rating. At the end, divide by the sum of the weights, not the total number of votes, and you have a weighted average.

It will probably take some kind of scaling factor for the weight - for example, if SO did something similar, it might be a little unfair to John Skeet to carry two hundred thousand times the weight of the registered new user opinion :)

+4
source

More articles:


All Articles