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| Who should be given a bye? http://www.lifein19x19.com/viewtopic.php?f=45&t=6803 |
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| Author: | Matti [ Fri Sep 21, 2012 6:04 am ] |
| Post subject: | Who should be given a bye? |
In a thread about [url]European Womens' Championship[/url] there was a question why a 2 dan get a bye on the first round and the answer was that slide pairing was used and she was 8th of 15 players. My question is:"Which player should be given a bye?" We assume that there exist a prior order for example: by rank, rating or qualification. I consider Swiss, McMahon and for reference knock out systems. Knock Out In Knock out it is best to give the top players a bye at the first round to make the number of players left a power of two. An alternate method playing a maximum number of games on each round and giving at most one bye at a time is problematic. Suppose there are 33 players. At first round player number 1 is given a bye and the remaining will be paired 2. vs. 33., 3. vs 32. etc. We have 17 players left. Suppose we don't want to give 1. another bye. and pair 1. vs 17. 2.bye, 3. vs. 16, 4 vs. 15 etc. Next round 3. gets a bye and 1. vs 9., 2. vs 8., 4. vs 7., 5. vs 6. Fourth round we have 4. bye, 1. vs. 5, 2. vs 3. Now on fifth round we have 1., 2., 4. left, who all have had a bye already. This is not very satisfactory. Swiss system A common idea is to give a bye to the lowest player who haven't yet had a bye. One wants to give the stronger players maximum number of games to resolve the top. Logically, if a bye equals to a win, it should be given to a strong player. If it equals to a tie, it should be given to an average player and if it equals to a loss it should be given to a weak player. This logic is seldom obeyed. Here are my ideas to give a bye with two examples. Bye is counted as a win. Assume the stronger players win against the weaker one. Swiss 7 players, 5 rounds: 1st round: 4. bye, 1. vs 7., 2. vs 6, 3. vs 5. 2nd round: 6. bye, 1. vs 4., 2. vs 3., 5. vs 7. etc. Swiss 15 players, 5 rounds: 1st round: 12. bye, 1. vs 15, 2. vs 14, 3. vs 13, 4. vs 11., etc. 2nd round: 11. bye, 1. vs 12., 2. vs. 7, 3. vs 6., 4. vs 5., 8. vs 15., 9. vs 14., 10. vs 13. 3rd round: 13. bye, etc. etc. With five rounds five players are going to get a bye. With 7 players, the 4th is among the players expected to get a bye and he is in the middle of the order. After the first round player 4 is with one point, ahead of 5,6 and 7. The next round is easy to pair. If a lower player were given a bye he would be ahead of some stronger player. The pairing of the next round would be biased. With 15 players, the middle player 8. would bee too high to get a bye. Therefore I would choose a player 1/4 from the bottom, who would be expected in getting a bye during the tournament. After two rounds the pairing would settle down. McMahon With McMahon one can apply the method of Swiss to the lowest group. Note With 15 players and 5 rounds In the Womens' European Championship it would have been possible to give the bye on the last round to the only player who had 4 wins. However in this case there should have been a decision in advance, before the end of the first round. |
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| Author: | topazg [ Fri Sep 21, 2012 6:19 am ] |
| Post subject: | Re: Who should be given a bye? |
My personal feeling is that it's a straw man to say that slide pairing means that 8th place gets a bye. I can't see why you can't argue just as well that 15th gets a bye (or lowest player that hasn't hasn't yet had a bye in subsequent round) and then pair the other 14th. I see only positives from doing it if I'm honest (apart from the weaker players having a considerably higher chance of missing a round with odd numbers of participants). As a separate question, was ghosting considered? |
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| Author: | ez4u [ Fri Sep 21, 2012 6:25 am ] |
| Post subject: | Re: Who should be given a bye? |
What is ghosting? |
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| Author: | topazg [ Fri Sep 21, 2012 6:37 am ] |
| Post subject: | Re: Who should be given a bye? |
ez4u wrote: What is ghosting? You have a player who's technically a non-competitor (quite often the organiser) who plays in the rounds where an odd number of people are present to make sure everyone gets to play the full number of games. The games count for all intents and purposes (ratings, results etc), but the ghost has no guarantee of playing any games, or which round(s) he'd be playing in. It's what most amateur tournaments in the UK seem to do, and it works well to keep everyone happy. |
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| Author: | RobertJasiek [ Fri Sep 21, 2012 6:48 am ] |
| Post subject: | Re: Who should be given a bye? |
A ghost is real player in the tournament list but not participating or is any extra bye besides the at most one regular BYE. Therefore tapazg seems to abuse the term for a different meaning, because intentional invention of ghosts is terrible and he would not mean that, I hope. BTW, the record ghost tournament was the EGC 1997 with a list of 590 "players", among which 51 were ghosts. EDIT: After topazg's clarification what he means, it is called Ersatzspieler, i.e., substitute player or sometimes called a "human bye". |
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| Author: | HermanHiddema [ Fri Sep 21, 2012 7:20 am ] |
| Post subject: | Re: Who should be given a bye? |
Byes should be given, IMO, in such a way that they are least likely to influence the outcome at the top of the tournament. For this reason, they should definitely not be given to the top players, as it might heavily influence the outcome in case of tiebreaks. On the other hand one should also avoid giving a Bye to the weakest players in the first round, because that player will then (because of the free point), be paired with the top players and could in that way influence the top of the tournament unduly. The ideal candidate in the first round, IMO, is therefore the weakest player from the top half, i.e. the middle player. For the same reason, BTW, in the second round the middle player from an odd sized top group should be preferred to be paired down. In later rounds, the strongest player from the bottom group is the best candidate from a BYE, as again such a player is least likely to unduly bias results at the top. |
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| Author: | topazg [ Fri Sep 21, 2012 7:25 am ] |
| Post subject: | Re: Who should be given a bye? |
RobertJasiek wrote: A ghost is real player in the tournament list but not participating or is any extra bye besides the at most one regular BYE. Therefore tapazg seems to abuse the term for a different meaning, because intentional invention of ghosts is terrible and he would not mean that, I hope. BTW, the record ghost tournament was the EGC 1997 with a list of 590 "players", among which 51 were ghosts. Quote: EDIT: After topazg's clarification what he means, it is called Ersatzspieler, i.e., substitute player or sometimes called a "human bye". Close, but my definition is how a ghost has often been referred to in this country, I promise that's not my invention. I have been asked to ghost in tournaments that I wasn't entered into before, simply because I was there accompanying someone else and the organisers had an odd number of players. Furthermore, even though I may be mistaken, I haven't heard of players who have had more than one bye being referred to as ghosts. I see nothing wrong at all with adding an extra player to make sure all rounds are played by all players, particularly if players have to travel and pay costs to be there. If that means inviting someone locally to play (who normally don't have to pay the cost to enter if they are there as an extra, as in each case I've been a "ghost"), then more the merrier for all involved. Do you have a link to any "official" definition of a ghost, as I'll be interested in seeing if I'm mistaken on the true defition (although I hope my question, definitions aside, is still clear)? HermanHiddema wrote: On the other hand one should also avoid giving a Bye to the weakest players in the first round, because that player will then (because of the free point), be paired with the top players and could in that way influence the top of the tournament unduly. By choosing the weakest player, you can award 0 points for the bye without having any real chance of affecting the final outcome of the tournament, nor give that player a miserable collection of following games (for obvious reasons). |
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| Author: | pwaldron [ Fri Sep 21, 2012 7:33 am ] |
| Post subject: | Re: Who should be given a bye? |
Ghost players have also been called "swing players" in my part of the world. This is a question that lends itself quite readily to simulation. Run some phantom tournaments with various bye methods and see which way produces the desired result most often. |
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| Author: | RobertJasiek [ Fri Sep 21, 2012 7:59 am ] |
| Post subject: | Re: Who should be given a bye? |
topazg wrote: Do you have a link to any "official" definition of a ghost I am not aware of any existing written official definition. My referred meaning of ghost has been consistently used in talks at tournaments since the 1990s. |
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| Author: | HermanHiddema [ Fri Sep 21, 2012 8:05 am ] |
| Post subject: | Re: Who should be given a bye? |
topazg wrote: HermanHiddema wrote: On the other hand one should also avoid giving a Bye to the weakest players in the first round, because that player will then (because of the free point), be paired with the top players and could in that way influence the top of the tournament unduly. By choosing the weakest player, you can award 0 points for the bye without having any real chance of affecting the final outcome of the tournament, nor give that player a miserable collection of following games (for obvious reasons). Everything I wrote was in the context of a Bye providing 1 point, which is the most usual way to handle them, in my experience. BTW, what you call ghost I know as joker, and the ghost usage I know is similar to what Robert describes. |
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| Author: | topazg [ Fri Sep 21, 2012 8:29 am ] |
| Post subject: | Re: Who should be given a bye? |
pwaldron wrote: Ghost players have also been called "swing players" in my part of the world. This is a question that lends itself quite readily to simulation. Run some phantom tournaments with various bye methods and see which way produces the desired result most often. If someone can throw me 15 players with relatively appropriate ranks (Matti, the actual ranks of the entrants would be useful, or GoRs of players), I'll run a bunch of tests with a number of variables |
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| Author: | Javaness2 [ Fri Sep 21, 2012 10:16 am ] |
| Post subject: | Re: Who should be given a bye? |
I'd normally give the bye to the weakest player... 1/2 a point topazg wrote: If someone can throw me 15 players with relatively appropriate ranks (Matti, the actual ranks of the entrants would be useful, or GoRs of players), I'll run a bunch of tests with a number of variables Just check the EGD 
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| Author: | topazg [ Fri Sep 21, 2012 12:34 pm ] |
| Post subject: | Re: Who should be given a bye? |
Javaness2 wrote: I'd normally give the bye to the weakest player... 1/2 a point topazg wrote: If someone can throw me 15 players with relatively appropriate ranks (Matti, the actual ranks of the entrants would be useful, or GoRs of players), I'll run a bunch of tests with a number of variables Just check the EGD Mmm, not up there yet 
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| Author: | Javaness2 [ Fri Sep 21, 2012 3:30 pm ] |
| Post subject: | Re: Who should be given a bye? |
http://www.europeangodatabase.eu/EGD/To ... y=T120907B |
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| Author: | Phelan [ Fri Sep 21, 2012 8:14 pm ] |
| Post subject: | Re: Who should be given a bye? |
HermanHiddema wrote: Byes should be given, IMO, in such a way that they are least likely to influence the outcome at the top of the tournament. For this reason, they should definitely not be given to the top players, as it might heavily influence the outcome in case of tiebreaks. On the other hand one should also avoid giving a Bye to the weakest players in the first round, because that player will then (because of the free point), be paired with the top players and could in that way influence the top of the tournament unduly. The ideal candidate in the first round, IMO, is therefore the weakest player from the top half, i.e. the middle player. For the same reason, BTW, in the second round the middle player from an odd sized top group should be preferred to be paired down. In later rounds, the strongest player from the bottom group is the best candidate from a BYE, as again such a player is least likely to unduly bias results at the top. I understand how having the weakest player as bye for first and second rounds might bias the results, but would the same keep happening after that? it seems that at that point, the best players would be likely to have 1 and two wins, and it would be hard for them to play a player with 0 wins. |
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| Author: | kivi [ Sat Sep 22, 2012 1:42 am ] |
| Post subject: | Re: Who should be given a bye? |
Phelan wrote: HermanHiddema wrote: In later rounds, the strongest player from the bottom group is the best candidate from a BYE, as again such a player is least likely to unduly bias results at the top. I understand how having the weakest player as bye for first and second rounds might bias the results, but would the same keep happening after that? it seems that at that point, the best players would be likely to have 1 and two wins, and it would be hard for them to play a player with 0 wins. As you say, in later rounds you don't have that problem, so it is ok to give bye to the weakest of the bottom group. Or random pick in the bottom group, rather than weakest. Actually, best is to pick random among the local players at the bottom, as it is worse for someone coming from far away to be forced to not play a round. |
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| Author: | Matti [ Sat Sep 22, 2012 7:38 am ] |
| Post subject: | Re: Who should be given a bye? |
HermanHiddema wrote: Byes should be given, IMO, in such a way that they are least likely to influence the outcome at the top of the tournament. Generally, I agree. However, what do you think about the idea to give a bye to the single player having four wins after four rounds? Then all the other players could have been paired without pairing anyone down or up.For this reason, they should definitely not be given to the top players, as it might heavily influence the outcome in case of tiebreaks. Quote: On the other hand one should also avoid giving a Bye to the weakest players in the first round, because that player will then (because of the free point), be paired with the top players and could in that way influence the top of the tournament unduly. In many cases, yes. But if the top half ios close in strength that any player would have a good chance of winning the tournament, I could consider another, weaker player. The ideal candidate in the first round, IMO, is therefore the weakest player from the top half, i.e. the middle player. Quote: For the same reason, BTW, in the second round the middle player from an odd sized top group should be preferred to be paired down. In later rounds, the strongest player from the bottom group is the best candidate from a BYE, as again such a player is least likely to unduly bias results at the top. This is possble, but slightly inconsistent with the first round. I might pick the middle one. |
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| Author: | RobertJasiek [ Sat Sep 22, 2012 8:04 am ] |
| Post subject: | Re: Who should be given a bye? |
Matti wrote: what do you think about the idea to give a bye to the single player having four wins after four rounds? Positive: his result is not over-determined. Negative: he is punished by not being allowed to play as many games as he had hoped for. |
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| Author: | Matti [ Sun Sep 23, 2012 11:54 pm ] |
| Post subject: | Pairing down (Re: Who should be given a bye?) |
We could extend the discussion to the question:"Who should be paired down?" HermanHiddema wrote: BTW, in the second round the middle player from an odd sized top group should be preferred to be paired down. I agree that the middle player from an odd sized top group is a good candidate to be paired down, but who should he play against? If we use slide pairing, then the opponents are generally half a group apart (by wins or Mcmahon points) and in fold pairing they are on average half a group apart. Following this logic the player paired down, should be given a player half a group lower, in this case the top player from the next group. However, by symmetry if we were to select a player to be be paired up from a group, also the best choice would be the middle player. Then we would pair middle players from two succesive groups and they would be about one group size apart. |
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