Draft:Swiss Draw in Ultimate Frisbee
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- Comment: Need more reliable non-affiliated coverage. :- ) DCS 19:02, 25 February 2012 (UTC)
Swiss Draw in Ultimate Frisbee is a tournament format coming from chess. It has been adapted to run tournaments in the sport of Ultimate Frisbee. The Swiss Draw format ensures that teams are ranked quickly according to their real strength and play close matches against opponents of similar strength.
- 1 Advantages / Disadvantages
- 2 History
- 3 Swiss draw Implementations
- 3.1 Rules used at Windmill 2013-2016
- 3.2 Rules used at Windmill Windup 2011 and 2012
- 3.3 Rules at Wonderful Copenhagen 2011
- 3.4 Rules at Talampaya 2011
- 3.5 Rules at Wisconsin Swiss 2011
- 4 Software
- 5 Media
- 6 Research
- 7 Other useful resources
- 8 References
- 9 External links
Advantages / Disadvantages
- using only a few rounds of play, the format quickly yields a ranking which better and better reflects the true strength of the teams
- teams often play teams of the same strength (-> fun for all)
- every point is important (also the losing team has to keep fighting)
- It is quite stressful for the organization to keep track of the scores when lots of teams are involved. The next round's matchups can only be computed when all results of the current round are known. If there's a delay with one game, the whole tournament (or division) will be delayed.
- Teams do not know beforehand where and against whom they will play the next round.
- format does not work well for few teams (<10) or too few rounds (<4)
- an odd number of teams creates unfairness
Here is a table of the tournaments and divisions which have used the Swiss draw systems so far:
|Year||Tournament||City, Country||Division||Nr of Teams|
|June 2017||Windmill Tournament||Amsterdam, NL||open||24|
|June 2017||Windmill Tournament||Amsterdam, NL||mixed||40|
|June 2017||Windmill Tournament||Amsterdam, NL||women||16|
|April 2017||Paganello||Paganello, IT||junior||10|
|April 2017||Paganello||Paganello, IT||mixed||26|
|April 2017||Paganello||Paganello, IT||open||10|
|June 2016||Windmill Tournament||Amsterdam, NL||open||24|
|June 2016||Windmill Tournament||Amsterdam, NL||mixed||40|
|June 2016||Windmill Tournament||Amsterdam, NL||women||16|
|June 2016||Wisconsin Swiss||Madison, WI, USA||open||26|
|June 2015||Windmill Tournament||Amsterdam, NL||open||40|
|June 2015||Windmill Tournament||Amsterdam, NL||mixed||24|
|June 2015||Windmill Tournament||Amsterdam, NL||women||16|
|June 2015||Wisconsin Swiss||Madison, WI, USA||open||28|
|March 2015||UKU Uni Mixed Nationals||Salford, United Kingdom||mixed||48|
|June 2014||Wisconsin Swiss||Madison, WI, USA||open||22|
|June 2014||Windmill Windup||Amsterdam, NL||open||40|
|June 2014||Windmill Windup||Amsterdam, NL||mixed||30|
|June 2014||Windmill Windup||Amsterdam, NL||women||18|
|June 2013||Wisconsin Swiss||Madison, WI, USA||open||26|
|June 2013||Windmill Windup||Amsterdam, NL||open||40|
|June 2013||Windmill Windup||Amsterdam, NL||mixed||24|
|June 2013||Windmill Windup||Amsterdam, NL||women||16|
|June 2012||Wisconsin Swiss||Madison, WI, USA||open||32|
|June 2012||Windmill Windup||Amsterdam, NL||open||40|
|June 2012||Windmill Windup||Amsterdam, NL||mixed||26|
|June 2012||Windmill Windup||Amsterdam, NL||women||14|
|November 2011||Ultimate Delhi-ght||Delhi, India||mixed||12|
|June 2011||Wisconsin Swiss||Madison, WI, USA||open||32|
|June 2011||Windmill Windup||Amsterdam, NL||open||41|
|June 2011||Windmill Windup||Amsterdam, NL||mixed||28|
|June 2011||Talampaya||Geneva, CH||mixed||34|
|May 2011||Wonderful Copenhagen||Copenhagen, DK||open||10|
|April 2011||University Ultimate Tournament||Amsterdam, NL||mixed||14|
|June 2010||Windmill Windup||Amsterdam, NL||open||38|
|June 2010||Windmill Windup||Amsterdam, NL||mixed||25|
|June 2010||Windmill Windup||Amsterdam, NL||women||16|
|June 2009||Windmill Windup||Amsterdam, NL||open||35|
|June 2009||Windmill Windup||Amsterdam, NL||mixed||18|
|June 2008||Windmill Windup||Amsterdam, NL||open||36|
|June 2007||Windmill Windup||Amsterdam, NL||open||21|
|June 2006||Windmill Windup||Amsterdam, NL||open||22|
|June 2005||Windmill Windup||Amsterdam, NL||open||24|
Swiss draw Implementations
Here is an overview over the detailed different rules employed so far.
Rules used at Windmill 2013-2016
First, teams are seeded according to our estimates of strength (actually determined by a public contest where users try to predict the final standings of the three divisions). The first Swissdraw round is meant to create a first good ordering of the teams. In this round, for 2n teams,
- seed 1 plays seed n+1,
- seed 2 vs. seed n+2,
- seed n-1 vs. seed 2n.
Instead of using victory points (described below) as in previous year, the teams were ranked by power rankings, a particular form of sports rating system. This ranking system has the advantage over victory points that it converges faster to a good ordering of the teams. However, it can only be computed by a machine, and possibly more difficult to understand.
Rules used at Windmill Windup 2011 and 2012
First, teams are seeded according to our estimates of strength. The first Swissdraw round is meant to create a first good ordering of the teams. In this round, for 2n teams,
- seed 1 plays seed n+1,
- seed 2 vs. seed n+2,
- seed n-1 vs. seed 2n.
In every game, the difference between scores is converted to Victory Points using the following scale.
|Margin of Victory||VPs for Winner||VPs for Loser|
So the maximum you can get is 25 VPs and the minimum 0.
This is popular because teams nearly always score something and the whole point of the draw system is that a team, clearly beaten, needs to battle to the finish as it is the margin which matters. Likewise, just winning is not winning much.
The ranking in the first round (after one game) is done according to:
- victory points
- total points scored
- spirit score (even though there are mostly no spirit scores available yet)
The ranking in the following rounds is done according to:
- number of games
- victory points
- sum of opponents' victory points
- total points scored
- spirit score
Creating new matchups
The draw for the next round simply consists of ranking the teams by VPs and resorting to allow that no team plays the same team twice. 1st plays 2nd, 3rd plays 4th etc. A team's VPs are carried forward throughout the tournament.
In more details, we go through the ranking from the top and check that the pairs 1-2, 3-4 etc. have not played each other. If you reach a team i which has played i+1, go further down the list to look for a team ranked j>i+1 which has not played team ranked i yet. Swap all the teams to get team j up to rank i+1. Continue the checks. If no team can be found further down the list, stop the procedure (but keep the obtained ranking) and reverse the direction: Go through the ranking from the bottom and check that the pairs 2n vs (2n-1), (2n-2) vs (2n-3) etc. have not played each other. If you reach a team i which has played i-1, go further up the list to look for a team ranked j<i-1 which has not played team ranked i yet. Swap all the teams in between to get team j down to rank i-1. Continue the checks. If no team can be found further up in the list, stop, keep the obtained ranking and start at a.
Do this enough times to get a feasible next round. There is no guarantee that this procedure will always work, but it also doesn’t look too bad. For only 5 rounds of Swissdraw and a minimal number of 16 teams per division, it should always find a valid next round.
Odd number of teams
Swissdraw pools always consist of an even number of teams. If there is an odd number of teams, a “ghost” team called BYE is added. The team playing BYE does not actually play this round and should not be assigned a field. There is a standard result assigned for that team in this round. For the victory points above, we use a 15-12 win for the team that has a BYE.
Otherwise, BYE figures like a regular team in the ranking: it moves down in the ranking, because it loses all games, and it is used as regular team when computing the sum of the opponent's victory points.
When moving to playoff rounds, the BYE team is left behind.
After the last round of Swissdraw, the teams are ranked and 1-8 go to the top playoff pool (for quarter, semi and finals), 9-16 to the next pool etc.
In case of an odd number of teams (or a number which is not a multiple of 8), special playout structures need to be used and things get messy. The tournament master should get a good overview at the end of Swissdraw of which teams already had a BYE. He then chooses a playoff structure which minimizes the chances that the same teams get another BYE. In the worst case, some things need to be adjusted manually. Usually this happens at the teams in the lower half of the ranking and they do not care too much anymore...
Rules at Wonderful Copenhagen 2011
The rules were almost the same as for Windmill 2011. A slightly different method for tie-breaking was used.
Rules at Talampaya 2011
The organizers have split the 34 teams into two pools of roughly even strength of 16 and 18 teams and ran seperate Swissdraws of 5 rounds for the two pools. For the organizers, this gave time to do the calculations of one pool while the other one was playing. On the other hand, it would be preferable to run all teams together in one big Swissdraw pool.
Rules at Wisconsin Swiss 2011
The rules  were very similar to the ones at Windmill 2011. For the ranking of the teams in the Swissdraw phase, an additional criterion, namely the number of wins, was used as primary ranking key.
The following software solutions have been developed for facilitating the running of Swiss draw.
The first five editions of Windmill Windup were run on Microsoft Excel spreadsheets enhanced with VBA macros. Another spreadsheet is provided by François Ganneau and Siddharth Rajagoplan on the Ultimate Central-blog
The open-source project UltiOrganizer provides (untested) support for running the Swissdraw format.
Another scoring-project called Stallcount9 has been successfully used at Windmill Windup 2011 to keep track of the scores. Advanced features include sending individual SMS to teams with the results of their last match and the coordinates (time and field) of their upcoming match. The software development has been stopped.
An American website. created and run by Mark Liu which aims at simplifying the life of tournament directors. The Wisconsin Swiss tournament was the first to use Leaguevine for fully online score-keeping by the teams themselves. The 2012,2013 and 2014 editions of Windmill Windup and Wisconsin Swiss have been using Leaguevine for score-keeping. It is the currently recommended system to use. A description of their algorithm was presented on their blog . It supports three different systems for ranking teams: regular (based on number of victories), victory points (according to score difference), and power rankings (least-square or Massey ratings)
It would be interesting to analyze the available historical data to see how "well" the Swiss draw system actually works. A visualisation project of the least-square ratings has been conducted by Casper Thuis as bachelor project in artificial intelligence at University of Amsterdam.
Other useful resources
- windmillwindup.com The largest Ultimate frisbee tournament on grass, held yearly in Amsterdam, NL.