Re:How Not to Sort by Average Rating (2009)
by panic on Wednesday August 30, 2017 @04:22PM
(#15135655)
You can also model each vote as an "agent" that tries its best to move the star rating toward its desired value. If the current rating is a 4, each "agent" with a vote less than 4 will throw a 1 into the average, and each vote greater than 4 will throw a 5. This process converges, though the rating tends strongly toward 3 (or whatever the middle value is).
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Re:How Not to Sort by Average Rating (2009)
by paulgb on Wednesday August 30, 2017 @06:00PM
(#15136458)
Good answer, this has a nice property that it can be applied to any reasonably behaved average-based system to get an honest mechanism. For a plain average it is equivalent to the median.
Re:How Not to Sort by Average Rating (2009)
by ajennings on Wednesday August 30, 2017 @06:56PM
(#15136814)
Not actually equivalent to the median.
If all the scores are 1s and 5s, then the median will be a 1 or a 5, but the average will be somewhere in between.
The problem is slightly easier to understand if we consider the grading scale from 0 to 100. Then every agent, trying to manipulate the score as much as they can toward their "ideal grade", will submit a grade of 0 or 100.
The average will converge to the unique number, X, where X percent of the graders want the final grade to be above (or equal to) X.