Rating

What is ELO rating ?

Your ELO rating for a game is your level at this game. It's a 4 digits number followed by sign .

Example: 1648 .

If you never play a game on BGA, your initial rating is 1500 . Each time you win a game your rating increases, and it decreases each time you lose a game.

How many points do I gain / lose for each game ?

ELO points gains / losses depend on the level of your opponents, and your rank at the end of the game. Some examples:

• If you end the game at a better place than a player with a higher ELO, you gain a lot of points.
• If you end the game at a better place than a player with a lower ELO, you gain less points.
• If you end the game at a worse place than a player with a lower ELO, you loose a lot points.
• And so on...

Some advice

• There's no use beating players a lot weaker than you (not many points to win). Try to find opponents of your level: it's both more fun and more good for your ELO.
• The number of ELO points you can gain/lose during a game increases with the number of players. The maximum is reached when there is the "recommended number of players". Try to play games with this recommended number of players.
• When you are the first player to quit a game in progress, you loose as many points as if you would finish the game at the last place, plus an additional penalty of 10 points. Even if you are in a difficult situation, your interest is to play the game until the end - or concede the victory to your opponent.

How is my ELO ranking computed ?

The BGA ELO system is directly based on the standard ELO rating system, in use for chess.

The ELO system main principle is the followin: the ELO points difference between 2 players determines the probability of each of them to win the encounter. If two players has the same ELO, their probability to win are 50/50. If one player has 400 more points than the other, his probability to win is 90%. ELO points gains and losses after each game tend to adjust ELO ratings of each player in order this principle is applied.

Okay, but I want to know the formula !

At first, when someone left a game for any reason this game is not taken into account by the ELO rating system.

• Table Level (TL) is the average of ELO ratings of all players at this table.
• The success (S) of a player depends directly on its ranking at the game, from S=+470 (winner of the game) to S=-470 (last player).
• The performance (P) of a player is TL+S.
• The new ELO rating (Rn) is a weighted average of the previous ELO rating (Rp) and the performance: Rn = K.P + (1-K).Rp

Good players, Experts, Masters

• Good players: > 1600 ELO
• Experts: > 1800 ELO
• Masters: > 2000 ELO