# Ranking FAQ

Q: ELO, what is that?

A: ELO is system to evaluate the strength of a player, it was originally developed for Chess.

The results from a game are evaluated by comparing the ELO-score from both players and the game result. The winner of a game receives a certain number of ELO-points from the loser. How many ELO-points one can win or lose in a certain game depends a.) on the result from that game and b.) on the relative rankings of the two opponents.

If one player has a much higher ELO-score it is assumed he will win. Accordingly he can get only a few points out of such a win. On the other hand should the lower ranked player win such a game he will receive quite a few points for that win.

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What is the ELO-score and how is it calculated?

The ELO-score was developed by the statistician Arpad Elo, who was creating a ranking system for the US Chess federation. The idea was to create a system that would allow make players and results more comparable and does not depend on an always somewhat arbitrationary classification of a players skill.

Today, the world ranking in Chess is done with the ELO-value.

For FOG set the average ELO-score to an arbitrationary score of 1600.

Upon being first included into the database, each player will be assigned these 1600 points as his starting ELO-score.

After each game, the ELO-score is recalculated depending on both players’ existing ELO-scores and the result of the game.

To start the winning probabilities for the players are calculated. As the player with the higher ELO-score is expected to be the better player, his winning probability is higher.

ELO-Difference | Win probability |
---|---|

0 | 50% |

5 | 50.7% |

10 | 51.4% |

20 | 52.8% |

50 | 57.1% |

100 | 64.0% |

200 | 76.0% |

300 | 84.9% |

400 | 90.9% |

500 | 94.7% |

1000 | 99.7% |

The table to the left shows the correlation between different ELO-scores and winning probabilities.

The larger the difference the higher the winning probability for the better player.

After determining the winning probabilities, the game value is calculated. This is defined to be the point difference from the game (Example: A game ends 25:0, so the game value is 25. If a games ends 6:14 the game value is 8)

In effect the higher the victory the more impact that game will have on the ELO-scores of the two players.

The ELO-change is then calculated using these 2 variables (the winning probability and the game value).**This is the formula:** ELO-change=2*game value*(1-winning probability_of_the_winner)

The value is rounded and added to the winners ELO. The losing player loses the same amount of ELO-points.

Here are 3 examples to demonstrate how this works:

**Example 1:**

ELO Player A: 1600

ELO Player B: 1600

Game result: A – B 19 : 6

The values are:

Game value = 13

Winning probability player A: 0.5 (=50%)

ELO-Change = 2 * 13 * (1-0.5) = 13

Player A is going to have his ELO-score raised by 13 points to a new total of 1613 as a result of this game while player B loses the 13 points for a new total of 1587.**Example 2:**

ELO Player A: 1800

ELO Player B: 1600

Game result: A – B 18 : 2

The values are:

Game value = 16

Winning probability player A: 0.76 (=76%)

ELO-Change: 2 * 16 * (1-0.76) = 7.68 = 8 (rounded)

Player A's ELO-score raises to 1808 as a result of this game, while player B goes down to an ELO-score of 1592.

**Example 3:**

ELO Player A: 1800

ELO Player B: 1600

Game result: A – B 2 : 18

The values are:

Game value = 16

Winning probability player B: 0.24 (=24%)

ELO-Change: 2 * 16 * (1-0.24) = 24.31 = 24 (rounded)

Player A's ELO-score goes down to 1776 while player B sees his EOL-score raise to 1624.

Example 2 and 3 show how the different winning probabilities help the weaker player to get more points out of a win vs. a stronger player than the stronger player does if he wins.

This makes the system perfectly designed even for games with players of very different skill levels.**Three extreme cases:**

- A DRAW will have no impact to the ELO-points of both players
- A player with an ELO-score that is more then 798 points higher than that of his opponent will not be able to gain any ELO-points from such a game, even by winning 25:0. This avoids a player to raise his ELO-score further and further by playing the same opponent over and over (granted not really a problem in a tournament environment).
- The maximum amount of ELO-point you can reap from a single game is 50. This requires winning 25:0 against an opponent with an ELO-Score 799 points or more over your own.

Q: The rankings look broken. Some ranks are missing while others are repeated two times or three times?

A: Well spotted, but this is intended. If two or more players have the same ELO-score, they will be ranked the same. The next player(s) behind them in the rankings receive the same rank as if the players before them had different rankings. Example: If three players have an ELO-Score of 1650 points, and the first of them will be rank 20th, the second and third are also ranked as 20th. Accordingly the ranks 21 and 22 are not assigned. The next player will be 23rd. This is similar to the rankings in some sports for example. We don't use any tie-breakers (like number of games or total points).

Q: Why has my ELO-score changed despite me not playing any tournament recently?

A: There are several possibilities: We are still adding results from new and also from older tournaments. As the ELO-score depends on the chronological order of games it might change due to the addition of an older tournament. All ELO’s for player from that tournament and those of anyone who played them at a later time have to be recalculated if an older tournament is included into the database. So the addition of an older Tournament can affect your ELO score directly (you played in that tournament) or indirectly (you later played someone who did played in that tournament).

Another more mundane possibility: We might have corrected an error in an older result. This also requires all affected ELO-scores to be recalculated and hence might cause the change to your ELO-Score.

Q: Where do you get your results from?

A: Nearly all of our results are taken from the Hall of Honour on the international Field of Glory Website. If a tournament is not there, it is most likely also not included in the ELO-rankings. Here you will find a list of all tournaments currently in the database.

Q: How are doubles affecting the ELO-score?

A: Doubles have no effect at all on the Single ELO-score. We do keep a separate Double ELO-Ranking though.

Q.: Tournament XYZ is missing in your database, can you please add it?

A.: Yes. Please send us the data. We are more than happy to have each (FoG:AM) tournament in our database.

The easiest way is to have an Excel or OpenOffice Calc sheet filled and sent to us via Email: **Important:** We can only include tournaments for which we are provided with the complete data required.

This includes: Tournament name, country, scale, number of rounds, player names, army names and especially all the results (by players and rounds, just the final standings are worthless to us, sorry).

While not strictly required, we also appreciate additional informations like, theme/period/book, the name of the umpire or any jumper, and similar.

Q: Why is my points-value not correct?

A: Most likely you have received a BYE at one or more occasions. These are not taken into account for the ELO-rankings.

Q: How can I get ranked?

A: That is simple. Take part in a tournament where the complete results are being sent by the organizers to us ( ) or to the webmaster of the FoG-webpage. If you took part in a tournament and you are not in yet, check if the tournament is listed here.

If not ask the organizer to sent us the results. Otherwise please mail us:

Q: Why are not all games counted for the Army-ELO?

A: All games are counted, except for games played versus an unknown army (to calculate an ELO you have to know both ELO-scores, obviously this isn't possible with an unknown oppoentn army). Similary games that had the same army on both sides cannot be counted as you cannot win AND lose ELO-points at the same time.

So these games will not have any influence at all.

Q: Is an ELO-ranking for armylists actually making sense?

A: It depends, the ELO system is intended to rate the skill of a player rating the quality of the player. since an army will be used by many different players this causes an obvious problem. Still using the ELO system to evaluate how different players are doing with one army can give some pointers as how adaptable that army is and how easy to use different players find it. For a meaningful result the number of games and players using it certainly needs to be notably higher then with a players ELO-score. If analysed in conjunction with the skill (i.e. the ELO-score) of the players that used a given army it is probably possible to draw certain conclusions how well an army works in the tournament environment.

Other questions? Send us an Email: