trueskill is arbitrary(tm) bullshit

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trueskill is arbitrary(tm) bullshit

Postby SeraphimLeftNut » 28 Jan 2016, 00:31

THE reference used to make this thread turned out to be BS.
This is not how FAF trueskill works.

Player A and player B
Au - player A skill
Ao - player A width of Gaussian around Au
Bu - player B skill
Bo - player B width of Gaussian around Bu

Coming into a game you have these 4 numbers, leaving the game you

will get those 4 numbers updated based on the outcome of the game.


if Au wins then
new Au = Au + Ao*(some arbitrary positive constant)*(some arbitrary positive function(not of Ao but of some other bs)*(Au-Bu)

if Au loses then change + to - above

new Ao = Ao*(1-some positive number)

So what we have here is a parameter Ao that always decreases with every game and makes the effect of future games on Au progressively smaller with the number of games.

Such a set up makes sense when you are studying entities that possess an underlying CONSTANT true Au that you are trying to figure out, essentially using the law of large numbers. The more you play the closer you will get to your true Au, assuming your true Au is constant.

Please tell me how this is not absurd.

ref. http://research.microsoft.com/en-us/pro ... tails.aspx
a very badly written BS piece
Last edited by SeraphimLeftNut on 28 Jan 2016, 23:11, edited 1 time in total.
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Re: trueskill is arbitrary(tm) bullshit

Postby Softly » 28 Jan 2016, 00:44

True I don't think a naive trueskill implementation is the best way to represent player skill since as you point out, people's abilities do not remain constant.

In the past FAF has used a custom implementation of trueskill however (not sure if this has changed yet, I know change is at least planned). This custom version had an effective floor on what Ao could reach (about 60). Its a bit of a hack, but does the trick. Its possible to adapt it so we have less of a hack and keep the benefit of Ao not falling too low.
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Re: trueskill is arbitrary(tm) bullshit

Postby d-_-b » 28 Jan 2016, 04:34

yes, it's really on obvious flaw in most rating systems, that they assume skill is constant.

some windowing (like, diminishing weighting of past games) would help, as if you play 1000 games then how well you did in your 20th game shouldn't matter at all, and rather than the extra information getting a more accurate rating of you now, it's adding in more noise than it is signal.
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Re: trueskill is arbitrary(tm) bullshit

Postby angus000 » 28 Jan 2016, 08:44

Totally agreed with you. When you explain it like that, it indeed makes no sense at all.
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Re: trueskill is arbitrary(tm) bullshit

Postby justmakenewgame » 28 Jan 2016, 09:06

i love how math lovers do researches and proves on obvious things.
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Re: trueskill is arbitrary(tm) bullshit

Postby lextoc » 28 Jan 2016, 09:19

SetonsGrandPa wrote:i love how math lovers do researches and proves on obvious things.

Not really contributive or appreciative.
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Re: trueskill is arbitrary(tm) bullshit

Postby Col_Walter_Kurtz » 28 Jan 2016, 13:08

Skill does have the tendency to level off the higher you get, though. So even though skill is not a constant you have to assume that large jumps are not warranted, the more games are on record. But I guess this is obvious already. Are there better systems out there, that correct for large jumps but allow for a more fluid skill development?
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Re: trueskill is arbitrary(tm) bullshit

Postby Voodoo » 28 Jan 2016, 13:45

The Elo-system is the best one in my eyes. It's easy to understand and you know before the game starts how much points you will lose\win.
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Re: trueskill is arbitrary(tm) bullshit

Postby Ithilis_Quo » 28 Jan 2016, 13:46

Im also big funn of ELO, its maybe not so complex as true skill, but its much more competetive, cleare and fun when know what is fighting for.
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Re: trueskill is arbitrary(tm) bullshit

Postby Sheeo » 28 Jan 2016, 14:48

viewtopic.php?f=42&t=11025

Trueskill is still a better alternative than ELO, which will just suffer from inflation over time.
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