# Rating system

## Tournament rating

To calculate the player rating in a backgammon tournament, we use the following formula:

R = 10 * log2(N) / M , where N – number of players in participating tournament, M – player’s place.

The rating obtained in the tournament will be added to the existing tournament.

Every month, the backgammon tournament rating is reduced by two. (R = R / 2)

Participate in backgammon tournaments more often to keep your rating high

## Backgammon Game Rating

Total and daily ratings are calculated as follows:

ratings are considered as follows oW in the event of a victory in a backgammon match, the player rating increases by the number of chips won.

If a player loses a game of backgammon, then his rating is reduced by 80% of the number of chips lost.

Daily rating is reduced by 5%. Therefore, play backgammon more often so as not to lose your place in the ranking.

## Elo rating

The developed Elo system was an American professor of physics at Markett University and a Hungarian-born chess player Arpad Elo ( Élő Árpád )

This system takes into account the strength of the players. If a strong player plays with a weak one, then in case of victory his rating will increase slightly. But in case of defeat, it will fall noticeably.

And vice versa, a weak player will win a noticeably higher rating, and if he loses, he will not lose much.

Initially, each new backgammon player receives a rating of 1500.

The change in Elo rating is calculated by the formula:

E = ± R * 10 * Sqrt( L ) / ( 1 + 10 D * Sqrt( L ) / 400  ) , where L – match to how many victory points (in money-games the value is 1); D – the difference in the Elo rating between the player for whom the rating is calculated and his opponent before the game; the ± sign is interpreted as follows: if won, the current rating increases, if lose, then subtracted; R – the coefficient taking into account how quickly the rating for new players will grow is determined by the formula:

If G is the total number of games for all time, then
if G> = 400, then R = 1, otherwise
if G <400, then R = (500 – G) / 100,
thus, newcomers will receive a larger change in ranking, starting with a fivefold decrease to 1 when 400 games are played.

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