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Epignosis View Drop Down
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Points: 32482 		Direct Link To This Post Topic: Top 20 Algorithm
    Posted: March 01 2009 at 16:33
Hi "PA's I Have a Question for You"-, long time listener, first time caller. 

I was simply curious about how the top 20 albums are calculated.  I understand how ratings are computed, but not how the top 20 albums of each sub genre are determined.  I notice that (as it probably should be), an album can have a few hundredths of a point less than another album and still be higher depending on the number of reviews.

The math geek within me, who rarely comes out to visit, has.  Geek 
https://epignosis.bandcamp.com/album/a-month-of-sundays
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Dean View Drop Down
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Points: 37575 		Direct Link To This Post Posted: March 01 2009 at 18:09
I think it's something like this ...
 
(Bayesian Weighting):
 
br = ( (avg_num_votes * avg_rating) + (this_num_votes * this_rating) ) / (avg_num_votes + this_num_votes)
 
 
 
Which means that an album with a few ratings can be lower in the chart than an album with more ratings and a lower average score.
What?
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Easy Livin View Drop Down
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Points: 15585 		Direct Link To This Post Posted: March 02 2009 at 02:39
If you click on one of the top album lists (on the right hand side of the home page), there is this brief explanation:
 
  • Rank of an album: We use a calculation that compare an album average rating over all others albums in the site using this theory (http://en.wikipedia.org/wiki/Weighted_average#Example)
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    Epignosis View Drop Down
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    Points: 32482     		Direct Link To This Post Posted: March 02 2009 at 07:53
    Thanks gentlemen.

    This will come in handy on some personal projects of mine.



    Like taking over Antarctica!  Evil Smile

    Seriously- I learned something today.  Smile
    https://epignosis.bandcamp.com/album/a-month-of-sundays
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    The Quiet One View Drop Down
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    Points: 15745     		Direct Link To This Post Posted: March 02 2009 at 12:41
    ^I wonder how does that algorithm, helps to take over Atarctica?Confused ErmmLOL
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    Dean View Drop Down
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    Points: 37575     		Direct Link To This Post Posted: March 02 2009 at 12:46
    ^it helps if you know the mean penguin density ratio - without that the algorithm is useless as the mean penguins will quickly over-power you and your invasion forces. Tsk! I thought everyone knew that. Geek
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    Epignosis View Drop Down
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    Points: 32482     		Direct Link To This Post Posted: March 02 2009 at 12:48
    Originally posted by cacho cacho wrote:

    ^I wonder how does that algorithm, helps to take over Atarctica?Confused ErmmLOL


    It is a complex plan involving the sacking of Argentina first.  Stern Smile
    https://epignosis.bandcamp.com/album/a-month-of-sundays
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    The Quiet One View Drop Down
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    Points: 15745     		Direct Link To This Post Posted: March 02 2009 at 12:49
    ^ErmmLet me take a few more reads, till I understand that........

    ......'2000 years later'......

    Nope, still don't get itStern Smile


    Edited by cacho - March 02 2009 at 12:50
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    The Quiet One View Drop Down
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    Points: 15745     		Direct Link To This Post Posted: March 02 2009 at 12:51
    Originally posted by Epignosis Epignosis wrote:

    Originally posted by cacho cacho wrote:

    ^I wonder how does that algorithm, helps to take over Atarctica?Confused ErmmLOL


    It is a complex plan involving the sacking of Argentina first.  Stern Smile


    Cry Take it! I'm dutch after all! muahahahahaEvil Smile
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    Epignosis View Drop Down
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    Points: 32482     		Direct Link To This Post Posted: March 02 2009 at 12:56
    Originally posted by cacho cacho wrote:

    Originally posted by Epignosis Epignosis wrote:

    Originally posted by cacho cacho wrote:

    ^I wonder how does that algorithm, helps to take over Atarctica?Confused ErmmLOL


    It is a complex plan involving the sacking of Argentina first.  Stern Smile


    Cry Take it! I'm dutch after all! muahahahahaEvil Smile


    We could team up, then!  You must bring chocolate and beer, however.  Tongue
    Smile

    Edited by Epignosis - March 02 2009 at 12:57
    https://epignosis.bandcamp.com/album/a-month-of-sundays
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    The Quiet One View Drop Down
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    Points: 15745     		Direct Link To This Post Posted: March 02 2009 at 12:57
    ^and you bring me a physical copy of Epignosis' Still the Waters, and it's a deal!
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    Epignosis View Drop Down
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    Points: 32482     		Direct Link To This Post Posted: March 02 2009 at 13:10
    Originally posted by cacho cacho wrote:

    ^and you bring me a physical copy of Epignosis' Still the Waters, and it's a deal!


    Sadly it doesn't exist yet.  I'd need $1000 for 1000 professional grade copies with a colored insert and all.  I was seriously going to wait until I could do that before making it widely available, but I decided it would never happen, knowing my saving skills.
    https://epignosis.bandcamp.com/album/a-month-of-sundays
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    Mr ProgFreak View Drop Down
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    Points: 5195     		Direct Link To This Post Posted: March 02 2009 at 13:17
    As pointed out in another thread a while ago: The documentation should link to this page instead:

    http://en.wikipedia.org/wiki/Bayesian_average
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    Points: 1818     		Direct Link To This Post Posted: March 03 2009 at 17:55
    I don't know if this has anything to do with the algorythm but I ve realized that some Miles davis albums like Kind of blue an bitches brew were at the top of the list a couple of weeks ago ( Specially Bitches that was in the top 25) and after one harsh review it dropped down up to 166 th position more or less.
    Has anyone noted this?
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    Desoc View Drop Down
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    Points: 216     		Direct Link To This Post Posted: April 10 2009 at 02:20
    ^ Yes, this is because the collaborator's ratings are weighted outrageously high when calculating album score. It has nothing to do with the algorithm, but with how each album's rating is calculated. Once this is established, the algorithm is then used to position the individual albums in relation to each other.
     
    Another example of the collaborator bias is this:
     
     
    which figured in the top 100 list for some time, then because one collaborator gave it a 1-star rating (without review or explanation, mind you) it fell as a rock.
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    Mr ProgFreak View Drop Down
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    Points: 5195     		Direct Link To This Post Posted: April 10 2009 at 02:50
    ^ I think that since this website favors reviews over ratings - and ratings without reviews aren't even visible on the album page - all ratings without reviews should have the same low weight, regardless of whether they're submitted by a collaborator.
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    Desoc View Drop Down
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    Points: 216     		Direct Link To This Post Posted: April 10 2009 at 02:54
    ^ On this I agree.
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    Dean View Drop Down
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    Points: 37575     		Direct Link To This Post Posted: April 10 2009 at 04:03
    ^ so do I
    What?
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