Changing the Rating Equation

[Defago]

Currently, the equation to determine an item's rating uses a Bayesian equation to avoid items with a low amount of ratings to crowd the top of the charts. Without this measure, an album with one single rating of 100 would be the most rated album on the whole site, which would make the Best Rated Albums chart useless.

The actual equation is as follows (taken from BEA's How Does It Work page)

Average Rating = (n ÷ (n + m)) × av + (m ÷ (n + m)) × AV

Which is more easily read as

Average Rating = (n × av + m × AV) / (n + m)

where
n is the amount of ratings received
m is a fixed value, currently 20
av is the average of all ratings received
AV is the average of all ratings on the site, which I'm estimating to be around 75

As mentioned before, the idea behind doing things this way instead of a regular, vanilla average is to avoid items jumping to the top with a single rating, because our top rated charts would be filled with unknown stuff which has gotten one single rating.

I'd like, however, to suggest reducing the "m" constant. It used to be fixed at 10, and then it was raised to 20 recently. Having such a high "m" value is negative, in my opinion. The core effect of this is that items with fewer ratings, regardless of the actual ratings, get a lower average. An item with ten ratings will have a maximum possible average of 83.

On one side, I understand the need to use the Bayesian average to avoid inaccuracies. However, I believe a reduced number such as 5 would do the trick, while also providing incentives for people to listen to new albums.

Example on both situations

m=5

An album gets five 100 ratings by members of the site, getting an average of 87.5 and climbing to the top of its year's Rated Chart. As it's on a higher spot and easier to see, people will listen to the album. Then they will either agree with the previous ratings, in which case the album is deserving of it's position, or they will disagree, in which case a couple of average ratings would drop it back to an intermediate position on that year's rated charts.

m=20

An album gets five 100 ratings. Its average is 80, which is barely enough for it to be noticed. Few people check it out, and a potentially good album is missed by the regulars.

I understand this would make the charts more volatile, but I don't see a problem with that. We already have a Ranked chart which measures popularity, it's unnecessary to have the Rated chart measure popularity as well. In my opinion, the Ranked chart should stay as it is, combining amount of charts with position, which takes into account both popularity and how much people like it; the Rated chart should try to leave popularity as much out as possible.

Also, a value of m of 5 wouldn't enable albums to rise to the top with a single rating - it's VERY hard to find an album with five 100's. If an album does get five 100's and rises to the top, then it's worth checking out at least. The people who check it and listen to it will decide whether it stays high or sinks low, in case the five ratings were not in accordance to what most raters think about the item in question.

tl;dr: Reduce the amount of invisible AV ratings. 20 is too high. Since we already have a chart measuring popularity, we should have the other chart exclude the "popularity" factor and concentrate on the "quality" factor.

All of this was done assuming an AV of 75, which while it might be wrong, the argument stands for any possible value it might take.

[Jabapac]

I could agree to get the m back to 10. but reduce the effect of amount of ratings too much is wrong I think. it's not about popularity over equality, but equality depends on popularity partly. they are not totally separated, because the more popular the more criticized.

[MrFrogger]

This is a good idea

[Defago]

[Happymeal]

I didn't even notice this suggestion. Interesting I guess. Wouldn't affect me personally either way so whichever, whatever.

[Guest]

I agree. As it is, I have no incentive to look over the top-rated albums list because pretty much everything there is pretty highly ranked, anyway.

[JMan]

I'm fine with the rating equation the way it is.

[Defago]

[HigherThanTheSun]

Yeah I like this idea. It relies on us checking the rated chart regularly and rating the top albums in case they've just got a small amount of really good ratings but that's cool I reckon, people would do it.

If it doesn't work can always be changed back anyway.
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Shut up mate you're boring!

[GeevyDallas]

This needs to happen