Swiss; Buchholz; Barrage explained

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PNZ has a set format for most two day National Championships, with more than 12 entries.  This is as follows:

Day 1 – Is all about finding the right seeding of players. This is done using five or six rounds of Swiss Format, using Buchholz numbers for tie breaking.
Day 2 – Is all about elimination in order to find the winners of the tournament. Barrage (a double elimination format) is used first which ultimately decides the top 4 or 8, followed by the next 4 or 8 etc. This is followed by a single elimination format or knockout so that 1st, 2nd 3rd … can be established. 

While these formats are explained in the Tournament Manual which can be found under tournaments on the website, many players have asked for explanations of these formats, so here is a simple explanation for each of them. 

What is a “Swiss Format”

A Swiss system format is a non-eliminating format which has a predetermined number of rounds based on the number of entries. Unlike a round robin, in a Swiss tournament, each team or player does not play every other team or player.  

In each round teams are paired using a predetermined set of rules designed to ensure that each competitor plays opponents with a similar score, or as similar as possible, but never plays the same opponent more than once.   This system then ranks teams or players from first to last in the tournament.    If there is an odd number of teams, then a bye is produced and is allocated to the lowest ranked team/player, but no team/player will be allocated more than one bye. 

The Swiss format provides a clear winner and reliable ranking using a limited number of rounds and allowing for a potentially unlimited number of opponents. It also means that all players play all rounds without requiring anyone to be eliminated.   It is difficult for players to “throw” a game to provide advantage to another team as to do so would affect who they play next.  It also has the advantage of teams/players not knowing who their next opposition will be until all games in a round are finished.

While the Swiss format can be done manually, it is complex, time consuming and open to error.   PNZ use a highly rated computer programme called the “Sport” software to operate the Swiss system format. 


 What are “Buchholz Numbers”?

The Buchholz Number system, is used by PNZ (and internationally) to calculate the final ranking in a tournament where teams are tied on the same number of wins.   It replaces using points differential to determine the final rankings.  It produces a superior ranking because it takes into account the quality of the opposition played.  This is important when teams are not playing every other team in the competition.   In effect you get a higher ranking by playing stronger opposition (as opposed to points differential where you get a higher ranking by playing weaker opposition).

Buchholz Numbers (BHN) are calculated from the total number of wins scored by every opponent your team played against during the day.   The more games your opponents win, the more BHN are awarded to you. 

BHN = The number of wins of every opponent you played, totalled together - 1 point for every win.  

If after calculating team wins and BHN’s two teams are still tied, another layer of tie breaking is required and Fine Buchholz (fBHN) are used.  fBHN are the total Buchholz Numbers all your opponents earned added to your own Buchholz Numbers.  

fBHN = Is the sum of all the BHN’s of all your opponents, plus your own

 

An Example - from a 6 round Swiss Tournament

 

Team A - has 3 Wins

 

Team C – has 3 Wins

 

Team D – has 3 Wins

A Played

No of Wins

fBHN

 

C Played

No of Wins

fBHN

 

D Played

No of Wins

fBHN

Team B

4

16

 

Team A

3

15

 

Team A

3

15

Team C

3

12

 

Team D

3

12

 

Team G

2

15

Team D

3

12

 

Team G

2

15

 

Team H

2

8

Team E

2

8

 

Team H

2

8

 

Team K

2

15

Team F

1

10

 

Team I

1

13

 

Team L

2

18

Team G

2

15

 

Team J

1

12

 

Team M

1

12

Total

15

73

 

Total

12

75

 

Total

12

          83

A’s BHN

 

          15

 

C’s BHN

 

          12

 

D’s BHN

 

          12

Total of opponents BHN’s (73)
+ A’s (15) = A’s fBHN                           88

 

Total of opponents BHN’s (75)
+ C’s (12) = C’s fBHN                           87  

 

Total of opponents BHN’s (83)
+ D’s (12) = D’s fBHN                            95

                         

Ranking of the 4 top teams

 

No of Wins

1st tie breaker (BHN)

2nd tie breaker (fBHN)

1st – Team B

4 Wins

13

89

2nd – Team A

3 Wins

15

88

3rd – Team D

3 Wins

12

95

4th – Team C

3 Wins

12

87

 

This system can be done manually, but again is complicated, time consuming and open to error.   PNZ use the “Sport” software” programme which calculates BHN and fBHN automatically.


What is a “Barrage”?

The Barrage format requires teams to be grouped into pools of four, so in PNZ Championships either 8 or 16 teams are taken into the Barrage sections, depending on the number of teams in the tournament. Teams / players are allocated to specific pools and who they play within that pool based on their ranked position from day one.  A set formula is used to determine these placements (see the tournament manual for this formula).

Barrage is a three round, double-elimination format, the objective is for teams/players to achieve two wins and qualify for the top section in the final deciding stage (knockout).   Not all players play the same number of games in Barrage; 50% play two rounds and 50% play three rounds depending on their wins and losses. 

Round 1 - the four teams in each pool play, producing two winners and two losers.

Round 2 – the two winners play each other and the two losers play each other, this produces one team with 2 wins (they go straight to the top section), two teams with 1 win each who need to play again, and one team with zero wins (they are eliminated to the lower section).

Round 3 – the two teams with 1 win each play off, this produces one team with two wins, who goes into the top section and the other team with 1 win is eliminated to the lower section.

In PNZ National Championships the top two qualifying teams from each pool progress to the Trophy or Plate Eliminations, while the bottom two teams progress to either the Trophy Consolation or the Plate Consolation Eliminations.

The advantages of the Barrage Format are; there are no byes or tie breaking procedures required as the format automatically ranks the teams/players. Teams/players do not progress based on differential just wins. It is difficult for players or teams to “throw” a game in order to help out another team.  It gives teams two chances to make the top section.


Single elimination format or knockout?

Once the teams or players are established for the final sections of the competition, a single elimination or knockout format is used to determine the final placings.    This involves two (semi-final and final) or three (quarter-final, semi-final and final) rounds depending on whether there are 4 or 8 players in each section.    Who plays who in this phase is determined by the placings in the Barrage rounds, again with a set formula.   Once a team has lost a game they are out of the competition.


For further information, please contact the Technical Director of Tournaments (barrie@andersonz.net)

Barrie Anderson
TD of Tournaments
June 2015

 

 

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