Statistical Analysis of Extended Series - Page 7

On November 13 2010 02:32 Risen wrote:


You're an idiot. These statements don't contradict each other at all...

On November 13 2010 02:32 Risen wrote:


You're an idiot. These statements don't contradict each other at all...

On November 13 2010 02:06 nzb wrote:


I imagine you would just use the initial seeds to sort between people with equivalent scores, and having 3x the number of rounds would quickly break people into categories.

I know that Google used this exact format (swiss->single elim) for their internal tournament at the end of the beta.

On November 13 2010 03:06 Jayrod wrote:
The extended series makes the finals of the tournament feel alot less epic. To be honest, I dont care whats fair to the players involved because the ONLY reason there is money involved is the viewership. No fans = No esports = no sponsors = no money for tournaments = tournaments would only be based on entrance fees etc.

If they want to make esports bigger, faster, they will understand that you want your finals to feel epic and last more than like 2 games. Its a really big let down to watch people battle it out to get to the end of this big tournament then have one guy playing with a handicap. I guess thats what happens with a double elimination style though... the extended series sucks.

On November 13 2010 04:20 Cyber_Cheese wrote:
early on in the article when explaining the series types a typo

"This rule is intended to avoid some paradoxical outcomes, as well as
statistically increase the likelihood that the 'better player'
continues in the tournament. It is possible in standard double
elimination for Alice to defeat Bob 2-1 in the winners', and Bob to
defeat Alice in the losers' 2-0. The "overall series" between Alice
and Bob is 3-2 in Alice's favor, but Bob continues and Alice does
not."

those should be 2-0, 2-1 and 3-2 in order to make sense

On November 13 2010 04:11 Ketara wrote:


The problem here is that sorting ties when using swiss pairing becomes astronomically more difficult the more ties you have.

Lets say we have 64 players, and we're using their sc2ranks scores to sort ties. The first round is sorted that way, which is fine. The nature of the system is such that the first round has to be somewhat arbitrary.

After the first round, you have 32 players with 1 win and 32 players with 0 wins. The 32 with 1 win haven't played each other yet, so their sc2ranks stats can be used to sort them, and the same for those with 0 points.

However, the problem then occurs in round 3, where we have 16 people with 2 points who haven't played each other, 16 with 0 points who haven't played each other, but 32 with 1 point who may have played the person with the closest rank in the first round. In fact, if the people with the higher ranks are consistently beating the people with the lower ranks, it is very likely that you will have a large portion of these 32 who's closest ranked opponent is the person they played in the first round.

Since by the rules of the system people cannot play each other twice (you could change that rule I suppose!) you are then looking for the second closest ranked person for every single one of your problem matchups. It doesn't take a math whiz to see that at this point, every matchup that is altered in turn alters every other matchup, and it becomes very ungainly to organize it if you have a large number of problem matchups. The pairing is supposed to be done by the system and the organizer is supposed to be unable to influence it, but at this point you have to be influencing it just in order to settle the pairings.

Doing accelerated pairings and having multiple games in a series, allowing for people to have a variance in their number of points per round, would mitigate this issue to a degree, but without seeing some math I'm not convinced that it would prevent it.

Further, the concept of using someones ranked ladder stats to sort teams is going to be full of problems, since not everybody ladders, the best players in tournaments are often not the best players on ladder, and Blizzard has stated that sc2ranks is not 100% accurate at sorting player skill level because we don't have the full equation on how the hidden MMR rating works.

It would probably be fine for the first round, because that has to be somewhat arbitrary, but by using it repeatedly round after round you're undermining the accuracy of your sorting method.

Obviously if you could get a tournament system going and seed players by earlier tournament scores this would stop being an issue, but there would have to be an initial tournament at some point, and it would be nice to create a system that could be used for one-off tournaments and not require them to be part of some sort of league.

On November 13 2010 06:05 Ketara wrote:
For our round 3 where the 32 players come up, lets see how sorting the next best player works. I'm going to use an 8 person example because that way I don't have to type as much.

We have 16 players, all with 1 point in the tournament so far:

Player A: 225 MMR, played E in round 1
Player B: 230 MMR, played H in round 1
Player C: 250 MMR, played a player who now has 2 points in round 1
Player D: 200 MMR, played F in round 1
Player E: 220 MMR, played A in round 1
Player F: 180 MMR, played D in round 1
Player G: 240 MMR, played a player who now has 2 points in round 1
Player H: 235 MMR, played B in round 1

Lets sort them from the top down.

C (250 MMR) plays G (240), which is straightforward.
H (235) should play B (230) but can't, so he goes to the next player down, A (225)
B (230) plays the #4 player, E (220)
This leaves D (200) and F (180), but they cannot play each other.

So now we have to sort it from the bottom up instead.

When you sort it that way it works out, but results in C and G not playing each other which was your only obvious matchup, and gives you F at 180 MMR playing E at 220 MMR, which is not entirely fair, because at that skill differential it is likely a free point for player E that was caused by ties in the system.

And that is only with 8 people. I dunno. It has the potential to work, it just seems difficult to me. I am betting that games that only count wins as either a win (1) or a loss (0) generally do not have 64 players in their swiss tournaments. The game that we use it for, Field of Glory, has a 25 point scoring system and a very reliable ELO ranking for players, and only one league for every tournament. Plus, our tournaments rarely break 20-25 people.

On November 13 2010 07:49 Ketara wrote:
Swiss ranking has a system for how many rounds you are supposed to have based on how many people have entered the tournament in order to achieve the best sorting, which as I understand it is because of that issue.

I think this is better than the wikipedia article: http://vtchess.info/Results/Swiss_Pairing_System.htm

"The rule of thumb is that it can handle 2n players, where n is the number of rounds. Therefore, 8 players needs 3 rounds, 16 players needs 4 rounds, 32 players needs 5 rounds, and so forth. (These numbers are approximations - due to draws and other variables, sometimes it works with more players than expected.)"

Using accelerated pairings allows you to have a tournament with 1 fewer rounds than what is necessary, but requires you to have a skill approximation of your players, and requires that you sort your initial round by that approximation.


Another note about swiss ranking is that there are actual literal ways to game the system. If you have access to the rankings and know everybodies score and who played whom and can do some quick math, you can at times figure out that if you lose a game on purpose, your next two opponents will be ones that you know cannot defeat you.

We call it "submarine-ing" and it's not a very honorable thing to do in our competitions but people do do it.

It is also sometimes possible to cheat the system by arranging a draw on purpose, but I imagine in Starcraft that would not be possible since draws are so difficult to create.