LEADER BOARD

    ELO Annual
Player Exp Rating Points Race
Tom Meyer 101 1538.55 35.5
Jay Karns 86 1532.59 26
Jim Sisti 111 1507.29 25
Sandy Sisti 96 1469.47 14.5
Al Cantito 84 1495.60 13.5
Al Theriault 50 1510.61 13
Mark Denihan 17 1528.48 11
Ross Gordon 15 1526.77 10
Ed Corey 68 1468.94 6.75
Jim Stutz 21 1511.00 6
Andy Fazekas 30 1500.55 4.75
Bill Porter 16 1500.01 2
Dave Mirto 21 1475.13 1
Frank V 37 1457.21 1
Rob Roy 23 1477.80 1

Updated 4/21/17

FIBS Rating Formula*

 

These are the formulas used to determine the ratings of a player:

 

Let's say that two players P1 and P2 were playing a n-point match. The ratings of the players are r1 for P1 and r2 for P2 .

 

Let D = abs(r1-r2) (rating difference)

Let P_upset = 1/(10^(D*sqrt(n)/2000)+1) (probability that underdog wins).

Let P=1-P_upset if the underdog wins and P=P_upset if the favorite wins.

 

For the winner:

Let K = max ( 1 , -experience/400+2 )

The rating change is: 4*K*sqrt(n)*P

 

For the loser:

Let K = max ( 1 , -experience/400+2 )

The rating change is: -4*K*sqrt(n)*P

 

The 'experience' of a player is the sum of the lengths of all matches a player has finished. Every player starts with a rating of 1500 and an experience of 0.

 

*Thanks to FIBS (First Internet Backgammon Server) for providing the rating formula as part of their HELP menu.