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.


Player Experience ELO Rating 2019 Points Race
Al Cantito 1482 1689.10 36.5
Ray Nilson 776 1486.85 28
Jim Sisti 1392 1547.61 23.75
Andy Fazekas 575 1512.33 23
Sandy Sisti 1223 1360.70 22.5
Ed Corey 1014 1437.20 18.75
Jerry Shea 980 1520.75 17
Derek Meredith 21 1507.29 7.5
Frank DiMaggio 24 1516.94 6
Adrian Costa 338 1405.14 3
Al Theriault 245 1496.30 2
Bill Porter 458 1629.57 1
Jim Stutz 188 1550.02 1
Jay Karns 826 1545.26 1

Updated 2/8/19


Annual Points Race Accrual Methodology


For each tournament event, Points are awarded to players as follows:


1.  A player receives 1 Point for each match they win and for every meetup they attend.


2.  Tournament Points are established based on the number of event participants and distributed thus:


A.  1st Place receives an amount equal to the total number of participants


B.  2nd Place receives an amount equal to one-half the total number of participants


C.  3rd Place (Optional) receives an amount equal to one-quarter the total number of participants


All tournament event points awarded to a player are added to their annual cumulative total.