Internet Movie Database, for calculating average ratings."/>
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help : Dropzone Database : How do you calculate the Top 10 DZs

How do you calculate the Top 10 DZs

We are using the same true Bayesian estimate formula used by the Internet Movie Database, for calculating average ratings.
weighted rank (WR) = (v / (v+m)) * R + (m / (v+m)) * C

   where:
      R = average review rating for the DZ = (Rating)
      v = number of reviews for the DZ = (votes)
      m = minimum reviews required to be listed in top 10
      C = the mean review rating across all DZs
This formula normalizes scores, that is it pulls a particular score (R) to the mean (C) if the number of reviews is not well above m. In other words, if a particular DZ has only a few reviews above the minimum required reviews to be listed in the top 10 (m), the average score is decreased a little if it is above the mean, or increased a little if it is below the mean in accordance with the normal distribution rule of statistics.

Here is an example:

   WR = (17 / 32) * 3.2 + (15 / 32) * 4.6 = 3.86
         |    |      |     |    |      |
         v   v+m     R     m   v+m     C
The formula normalizes the average rating of a relatively low rated DZ/Tunnel from 3.2 to 3.86 since the number of reviews (v=17) is only slightly above the minimum required votes (m=15) and the mean across all DZs (C=4.6) is quite high. If, in the future, this particular DZ/Tunnel gets more reviews, the difference between R and C will increase as the number of reviews increase. The idea is that the more reviews, the more representative the average rating is.




By on 2004-10-29 | Last Modified on 2014-02-28

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