A Backgammon Swiss: Participation

Last weekend I ran a 32-player backgammon tourney using true Swiss system pairings rather than the more usual bracketed elimination format.

There is much to consider in choosing between the two styles. In this post, I’ll consider the most obvious differences from the standpoint of participation.

First, consider the more usual approach, a bracketed tourney with a consolation flight. Brackets for a 32-player event can be found here: 32upper, and 32ABCDvv.

Backgammon tourneys tend to run long. A conventional full double-elimination tourney for 32 runs 10 rounds, or 11 with a possible recharge. We didn’t have time for that. So, I save rounds in three ways: I save at least one round, and possibly two (with a recharge), by making the lower bracket a consolation rather than a second chance to win the overall tourney. I save another round by not dropping the losing finalist from the upper bracket, and another by shifting the lower bracket.

Considering that the lower bracket can’t begin until the first round of the upper is played, that means that the streamlined tourney will still take seven rounds. There will be 60 matches in all, arranged in rounds thus: 16, 16, 12, 8, 5, 2, 1. For the first two rounds, everyone gets to play. But as play progresses the play will thin out. The average number of matches per player is 3.75, but they are not evenly distributed. Eight players will get only two matches, eight will get three, six will get four, six more will get five, two will get six, and two will get seven. Such a tourney will often play four places, with prize money allotted in thus: 45%, 22%, 22%, and 11%, for the upper winner, the upper finalist, the lower winner, and the lower finalist, respectively.

Compare, now, the Swiss system tourney for the same number of players. To find a single winner, it will need five rounds, but everyone plays all five rounds, so that a total of 80 matches are played: 16, 16, 16, 16, 16. Because there happened to be exactly 32 players, there will be a single winner with a 5-0 record, and five players tied for second through sixth places at 4-1. I distributed the prize money about 40%, 12%, 12%, 12%, 12%, and 12%.

The advantage in terms of participation is obvious – we played 20 more matches. And we distributed them more evenly, with everyone getting to play exactly five. So, on this point, at least, the Swiss format is clearly superior.

And for the most part, that’s how the participants in Saturday’s event felt. But there were some whose reaction was a bit cool. The players who did well, and thus would have played at least five rounds under the old format, tended to be somewhat less enthusiastic for the Swiss.

Even overlooking the coolness of some of the better players, the case for the Swiss is not yet clear because there are other factors to consider (in future posts).

One additional note that belongs, perhaps, to the participation factor of the FEPS analysis: the Swiss system tournament software I used has a feature that my players were glad of, as it enhanced the quality of the participation as well as the quantity. A common complaint about other tournaments is that a player can travel a long distance to reach the site of a tournament only to find that they are paired against a player from their own local club, who they play all the time. The WinTD software I used can be made to avoid pairings of players who belong to the same local club unless such pairings are really necessary.

One thought on “A Backgammon Swiss: Participation”

  1. I’ve got an eight-round Page32DE that maths out in the following way:

    W | L sides
    1st Round: 32 | 0
    2nd Round: 16 | 16
    3rd Round: 8 | 16
    4th Round: 4 | 12
    5th Round: 2 | 8
    6th Round: 1 | 5
    7th Round: 0 | 4 **OR** 1 | 2
    8th Round: 2

    Key quirks:
    I typically have teams with losses at the same time play each other in loser’s brackets. The earliest rematches would happen in Round 6.

    The six remaining teams in Round 6 are W0, L1, L2, L3, L4, L5 – named after the round they lost in.

    Round 6 games: W0 vs. L3, L1 vs. L4, L2 vs. L5
    Round 7 games: If W0 won, they get a bye into the final. The remaining two teams play.
    If W0 lost, they must play winner of L1 vs. L4.
    Round 8: 2 teams are left. W0’s potential bye counts as a loss for DE purposes.

    I haven’t been able to determine a very good consolation bracket for this yet, but believe another small DE could be staged as the (12 | 4) combo will PageDE in an acceptable way. These compromises open the door for other “fair” brackets, and I’ve found suitable ones at 7, 8, 13, 14, 22, 24, 26, and 40.

    Like

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