Tournament types pros and cons

McMahon

Recommended pairing method: Strength

Pros:

  1. Only one game at a time (light load on players).
  2. The director can control number of rounds.

Cons:

  1. Weaker players may have no chance of winning depending on McMahon bars.
  2. Burden on the director to correctly choose McMahon bars and Number of rounds.

Simultaneous McMahon

Recommended pairing method: Strength

Pros:

  1. Players get to play more games compared to other systems.
  2. The director can control number of rounds.

Cons:

  1. Multiple games at the same time (high load on players).
  2. Weaker players may have no chance of winning depending on McMahon bars.
  3. Burden on the director to correctly choose McMahon bars and Number of rounds.

Round Robin

Pros:

  1. Easy to understand.
  2. Relatively short.
  3. Every player has a chance to win.

Cons:

  1. Maximum number of players is capped at 10
  2. Multiple games at the same time.

Swiss

Recommended pairing method: Strength

Pros:

  1. Every player has a chance to win.
  2. Only one game at a time.

Cons:

  1. Relatively larger number of rounds.

Single Elimination & Double Elimination

Recommended pairing method: Slide or Slaughter

Pros:

  1. Every player has a chance to win.
  2. Only one game at a time.

Cons:

  1. Players don’t get to play the whole tournament.
  2. Very uneven games.
  3. Relatively larger number of rounds.
10 Likes

Or they could edit the point values after the tourney starts if they think that the points are uneven.

2 Likes

McMahon - Con - Scores can easily be tied making it so the good people have the best shot of winning, even when the tourney is made to be even.

1 Like

Just don’t use the default pairing methods to prevent this issue.

1 Like

This is my personal bias, but I think I’ll prefer Round Robins, since I’m playing everyone and I can tell if they are AWOL. This applies to my personal preference for fast(er) tournaments, of course.

(A player is TM in 2 tournaments, one RR (TM participates) the other some other type (TM doesn’t participate), the same player is AWOL in both tournaments for weeks. In the 1st he was DQ’d, the second is in limbo.)

2 Likes

In McMahon this is a feature not a con right? I thought the whole point of McMahon is that players who have a realistic chance of winning are above the bar and untroubled by having to play those who have no realistic chance of winning. Hence there can be fewer rounds but the “correct” winner can still be found.
The benefit for the rest of the field is close even games which increase the accuracy of their ranking.

I think the problem with ogs McMahon tournaments is that the pairings should be made by MMS but I’m not sure this is an option. And the bar needs to be set after the number and strengths of participants is known but I’m not sure this is possible either.
(I’ve never run a run a tourney on ogs so don’t really know how it works here. My experience is with irl tourneys)

Turns out you can write quite a bit about setting the McMahon bar! www.kaniuk.co.uk/articles/pairing/mcmahon-bar.pdf

Isn’t the pro here that there can be fewer rounds? The director shouldn’t really “control” this, they should just set the fewest rounds that can determine a winner given the likely size of the group above the bar? I.e. related to the number of participants

6 Likes

Is this actually a thing?
Simul McM is based on groups that are arranged on strength by definition. What is pairing about, then?

This is a question I have in mind since my first participation in a Simul McM tournament, so I am really looking for explanation.
Sometimes you see “pairing: slaughter” but you always play opponents that are about your strength

3 Likes

For what it’s worth, I feel a comment is needed on the pros and cons. I feel all of the things listed above represent “attributes” of the tournament types rather than pros or cons. For example, I consider the multiple games at the same time a pro for tournaments. As you want to collect enough data to produce a clear winner, I feel more games = more data, therefore I like it. I am aware some people would rather focus on a single game at a time, but that’s my point really, it’s subjective preference. I’m fairly convinced that “every player has a chance to win” isn’t necessarily a positive. Let’s be honest, other than including handicaps, a 10 kyu doesn’t have a chance to win a tournament with a 2 dan and a 5 dan in. It’s mathematically possible, but that’s not the same thing - and the downside can be that a 5 dan doesn’t really enjoy his early games because he’s giving that 10 kyu his “chance to win” and frankly he’s finding it a tad boring … yes, ok, “why did he join then?” etc etc, but we’re talking about pros and cons, and my point someone’s pro might be someone else’s con.

I do think it’s a good collection of points about each tournament type, I just wouldn’t group them into plus and minus points

4 Likes

Simultaneous McMahon is the only tournament type with working point pairing.

1 Like

They still have to correctly do that. It’s still the same burden.

Then it messes with the chances of the strongest player winning. In most sports they do at least some tricks to make stronger players last more rounds.

It’s a con, I think. The feature is that we can have fewer rounds and more even games from the get-go. But it comes at a cost. More correctly would be “players with lower rank don’t have a chance to win”. More on it later.

Well, for better or worse, the director does control the number of rounds on OGS. And most would have no idea what the correct value should be and probably set it from experience.

Probably, the trick is that even if you choose other pairing, Strength is used. So it doesn’t really matter, but I think it’s better to choose the “correct” pairing still.

@topazg I believe we can separate pros and cons if we choose the words wisely. Higher workload on players is likely a con. But at the same time more exciting games and more data for better winner determination can be written into pros. “If you play good, you’ll win the tournament” is positive. In McMahons there’s possibility of a weaker player who had a good run or improved since the last tournament (or improved since the tournament started) will win all the games but won’t be first. For example, they can even win against the player who ended up 1st but take the second place because of starting points. Even a possibility of this is bad.

If it’s so then we can just put it in the cons there, and there’s no contradiction.

Ha! Usual McMahon and Swiss also pair people with same number of points together (try to anyway). Pairing method should be strength in order for it to work (that’s not how normal Swiss works, I know, but it sort of works ok)


Anyway, I think if we correct the language here and there, add the explanation about how the types work in general. We could add it into the wiki.

2 Likes

Yeah, isnt this the whole idea of McMahon points? You dont need as many rounds to find out who’s the best player of the tournament. Of course the fairest format is always the round robin, but with tens or hundreds of players and/or in live setting rr gets almost impossible to pull of. And still someone who isnt within the top ranks has no realistic way of winning the tournament.

I imagine mcmahon tournaments being like i’m starting an round robin tournament after 3/4 of the games having already been played (the lobsided games against 20k’s and 6d’s) with the stronger player winning. So now when the tournament starts, i only have those games remaining which are against ppl close to my rank, because they are the ones whom i’m competing against.

5 Likes

Actually, probably not for correspondence Go. This would be hilarious for a 200 player tournament. I think I’d sign up on principle.

3 Likes

Two things here. I think one problem is the desire for a sequence of wins in a tournament to be recognised somehow. In real life McMahon that I know, winners of three games (assuming a three round tourney) get a prize, often almost as good as the winner’s prize as well as the fact that they will surely gain ranking points. (The winner of course gets the glory of winning too). Whereas online there are no prizes beyond the glory.

The other thing is that if a player beats the winner but doesn’t win because of the McMahon points then the bar was set incorrectly. The only way for this to happen in a correct McMahon tourney would be for the tourney winner to win their other two games and for the second place player to lose their other two games (or maybe win one against a weaker opponent). I think this would give the "correct"result. If the tournament winner won the tourney winning fewer games than the second place player the fault lies with the TD not the McMahon format.

3 Likes

Sequence of all wins means only that the starting ratings are wrong, aka the player was sandbagging. It’s rewarded because it supposedly shows the progress the player made. But for example, if I haven’t played for 2 years and showed up 5 stones stronger than my old rating probably I can win everything.

Same with beating the winner case. It’s not necessarily about McMahon bars, it can be because of inaccurate starting rating also. And in that case it’s not TD’s fault. (Plus in McMahon a lot depend on coefficients because of too few rounds)

That’s the flaw in McMahon. You need accurate ratings for it to work. “Strongest player wins” doesn’t work. It’s “strongest player + good enough starting rating”. And we don’t always have accurate ratings.

For example, right now in corona times there’re no offline Russian tournaments and online tournaments aren’t rated (because cheating). So in unrated online tournaments everyone has inaccurate ratings, pairings and starting points are all over the place. It’s also a bit worse because ratings are basically derived from different player pools. Moscow ratings differ from Khabarovsk and so on.

On OGS we have it better with ratings but since one round can take 6 months or more it can be unfair too.

5 Likes

Yes ok this is a problem. So the con for McMahon is not that weaker players have no chance of winning but that this format giving a satisfactory outcome is dependent on accurate ratings.

Why not. If we can get enough people to knowingly commit to something like this. I bet if we invite random people, most would immediately resign upon seeing what exactly they signed up for.

3 Likes