LEADER BOARD

    ELO Annual
Player Exp Rating Points Race
Tom Meyer 52 1518.66 19.5
Jay Karns 69 1506.82 17
Jim Sisti 69 1511.85 16
Sandy Sisti 55 1487.87 11.5
Ross Gordon 15 1526.77 10
Al Theriault 34 1497.29 8
Al Cantito 67 1489.48 7.5
Jim Stutz 21 1511.00 6
Ed Corey 33 1510.56 5.75
Bill Porter 16 1500.01 2
Dave Mirto 11 1491.44 1
Rob Roy 8 1484.85 0
Andy Fazekas 10 1482.17 0
Frank V. 12 1481.23 0

Updated 3/24/17

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.