This should be an example calculator for a possible bbc rating. The aim of the rating is to estimate the current strength of a player as good as possible.

This page uses the rating 5.

You do not need to know the full details on how the rating will be computed, because this is very complicated. Here are some basic principles:

- you start with a number of rating points. after each game you will win or loose points, depending on how good you play.
- the place you get in a game has a big influence on how many points you make.
- If you play against players with a higher rating than yours and are successful, you get many rating points
- If you play against players with a higher rating than yours and are not successful, you loose a few rating points
- If you play against players with a lower rating than yours and are successful, you win a few rating points
- If you play against players with a lower rating than yours and are not successful, you loose many rating points

If you want to know, how things look like if you consider many games, here is an example computation: (click here). it uses all BBC games in 2013. you can even get a graph of players of their rating over time.

Place | Old Rating | New Rating | Difference | played games |
---|---|---|---|---|

1 | 5000 | 5421 | 421 | 1 |

2 | 5000 | 5273 | 273 | 1 |

3 | 5000 | 5193 | 193 | 1 |

4 | 5000 | 5113 | 113 | 1 |

5 | 5000 | 5033 | 33 | 1 |

6 | 5000 | 4953 | -47 | 1 |

7 | 5000 | 4873 | -127 | 1 |

8 | 5000 | 4793 | -207 | 1 |

9 | 5000 | 4713 | -287 | 1 |

10 | 5000 | 4633 | -367 | 1 |

function noobratingmain($ratings,$gamec,$probdiff=3000,$startspeed=80,$minspeed=40,$mingames=30,$winbonus=1.17) { /* this is the core function of the bbc rating. it was programmed by some supernoob :) $ratings and $gamec are arrays of the same size the size is the number of players player with index 0 is winner, 9 is place 10 gamec is the number of games played before this game */ if(count($ratings) !=count($gamec) or count($ratings)>=11) return 0; //error $NN=count($ratings); // $NN is the number of players in the game $newrating=$ratings; // newrating will be return array for($i1=0;$i1<$NN;$i1++) { $expect=0.0; // $expect is the expected score for each player for($i2=0;$i2<$NN;$i2++) { if($i1==$i2) continue; $diff = (float)($ratings[$i2]-$ratings[$i1]); //compare rating difference with each player if($i2==0 or $i1==0) $expect += $winbonus/(1.0 + pow(2.0,$diff/$probdiff)); // add expected score for winners if($i2!=0 and $i1!=0) $expect += 1.0/(1.0 + pow(2.0,$diff/$probdiff)); // add expected score for non-winners } if($gamec[$i1]<$mingames) $speed2 = (float)$startspeed + (float)($minspeed-$startspeed)*($gamec[$i1])/($mingames); if($gamec[$i1]>=$mingames)$speed2=$minspeed; // determine the "speed" according to parameters $wonpoints=$NN-$i1-1; // if($i1==0) $wonpoints=$winbonus*9.0; // winners get more points $newrating[$i1] =$ratings[$i1] + (int) ceil($speed2*($wonpoints - $expect) -0.5); //round the rating points to integer } return $newrating; }

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