Ratings Calculation.jpgASPCC Ratings

by Steven Ledford

 

 

Ratings Report for KK 319 -- Ratings Order

 

All players with established ratings (1 game against opponents with established ratings) and current membership.  An initial rating was assigned to Charles Carter (congratulations!). All players with provisional ratings (0-9 games against opponents with
established ratings) and current membership.

Bates, Michael W. 2583
Miettinen, Kristo 2392
Ledford, Steven Sr. 2350
Moore, Bobby Jr. 2319
Quirk, Michael P 2308
Vaughan, Stan 2307
O'Keefe, Michael J. 2273
Cotten, Donald R. 2269
McDaniel, Curtis W. 2268
Hansen, Christopher 2261
Barry, Robert F 2249
Lawrence, Caesar 2240
Marshall, Michael J 2236
Belter, Ralph 2211
Eisenberg, Robert 2177
Simpson, William 2174
Hill, Beamon B. 2167
Hecht, Simon W. 2158
Mulford, Michael A. 2123
Carter, Maurice 2117
Ovall, Larry 2087
Moore, David 1997
Plonas, Kerry 1992
Molina, Carlos 1961
Avena, Carlos 1958
Walker, John G. 1943
Sikes, Haskel 1938
Waibel, Klaus 1938
Slater, Robert W. 1935
Storr, William R. 1921
Daffin, Charles H. 1901
Hernandez, Julian A 1891
Scott, Herman B. 1888
Mercer, Larry 1886
Chabassol, Wade E. 1885
Rodriguez, Juan 1885
Henock, Roy 1877
Royer, Dale 1875
Schoolcraft, Daniel 1868
Bruner, David 1836
Paine, Stephen W. 1832
Peter, George Jr. 1832
Jirousek, Jim 1827
Floyd, Jesse 1823
Wyatt, Norman W. 1821
Groleau, James 1819
Stephen, Walter 1812
Hawks, Robby 1811
Covington, M. Paul 1807
Vanderbeek, Charles G.1807
Donaghy, G. R 1803
Johnson, Lowell E 1797

Ng, Willy C. 1797
Slechta, David J. 1797
Sedlmayer, Walter 1778
Myers, Matthew 1754
Chamberlin, Paul 1749
King, Z. L. 1732
Evans, Stanley 1726
Buschmann, Andrew 1718
Conti, Frank P. 1711
Dostal, Don J. 1704
Kappel, Ray D. 1700
Chranowski, Charles 1697
Singleton, Manuel M 1696
Carter, Charles 1682
Austin, John H. 1670
Brotze, Robert J 1668
Borne, Lawrence 1653
Kay, Richard 1650
Waddell, Thomas 1642
Kares Danny 1636
Papowitz, Eugene 1636
Ware, Michael 1629
Smiley, William R. 1622
Best, Herbert E 1614
Nolan, Dorothy 1612
Hrabovsky, Stephen 1600
Fisher, Harry 1596
Spooner, Frank R. Sr. 1593
Martin, George H. 1579
Terry, David R. 1555
Lane, Riley 1546
Fadigan, Joseph 1544
MacDonald, Robert A. 1542
Dippel, Jim 1536
Sasseen, John 1535
Shearer, Robert E. 1524
Gast, Levi 1519
Anderson, Lawrence D 1498
Strunk, Larry 1489
Hobson, Nathaniel D. 1481
Gibson, Jeffry R. 1477
Moenich, Neal W 1475
Brown, James R. 1452
Luoma, Everett E. 1447
MacDermid, B. W. 1443
Bautista, Eric 1437
Ezzell, Johnny 1354
Rosenheim, Harold 1324
Miller, Patrick A. 1314
Fawcett, John L. 1281
Benjamin, James M 1278
Ratcliff, Kenneth 1278

All players with provisional ratings (0 postal games against opponents with established ratings and current membership
Tucker, Stacy
Kelper, Archie
McKellop, Thomas 2184
Lowery, Jonah 1850
Booker, Andrey 1700
Swicegood, Jim 1650
Burwell Nicholas 1600
Chappell, Alan 1600
Frank, Reginald 1600
Issawi, Sami 1600
Telker, John. 1600
LeMar Jack 1500
Sanders, Keith 1200

Greatest increase

Donaghy, G. R – 33+


Senior Master
2400+
Master
2200-2399
Expert
2000-2199
Class A
1800-1999
Class B
1600-1799
Class C
1400-1599
Class D
1200-1399
Class E 
0-1199

 

Overview of the rating system

                The rating system implemented for ASPCC is Arpad Elo’s system with a fixed weight per game and logistic scoring expectation function. For games played between players with established ratings, this means essentially that the game is a wager for 32 rating points, with each player contributing a portion of the 32 points to the “pot” in proportion to their odds of winning (estimated from previous ratings).  The 32 points then go to the winner (minus the winner’s contribution to the pot), while the loser loses their contribution to the pot.  In the event of a draw, each player gets 16 points, minus their contribution to the pot.  The contributions are taken out at the same time as the game is rated, i.e. there is no “pay now, win later” delay in adjusting ratings. The scoring expectation function and the contribution to the 32-point pot can be computed for each player form the following formula:

Expected score = 1/(1+exp[(his_rating-my_rating) /166.2])
Contribution = 32*expected score

The expression “exp” represents the exponentiation function, available in Excel with that name, or on any scientific calculator with the key labeled “ex”.

To take an example, suppose that player A has a rating of 1450, and player B has a rating of 1320, and they play a game.  What happens in each of the three cases (win/lose/draw)?
First, nothing happens until the game ends.  So, if the ratings of the two players change during the course of the game because of other games finishing, then it is the most recent ratings that count.  In the case of ASPCC games, all results published in any one issue of King’s Korner are rated simultaneously, using as the “previous” rating the rating list published in that same issue.  For instance, the ratings list published here in KK266 is based on the formulae above, applied to each game reported by a TS in KK265, and using the ratings list in KK265 for the ratings in the formulae (“his_rating” and “my_rating”).

So, to make the example concrete, let’s stipulate that the ratings for player A and player B in the example were published in KK265, and so was the result of their game, and neither player A nor player B had any other results published in KK265.

Then, we can calculate the expected result of their game: player A’s expected score is 0.686, while player B’s expected score is 0.314.  Each player contributes rating points to the wager in these proportions, so player A contributes 22 points, while player B contributes 10 points (for a total of 32 points).

If Player A wins, he gains 32 minus 22 points, or 10 points, and has a new rating of 1460, while player B loses 10 points and has a new rating of 1310.  On the other hand, if player B wins then he gains 32 minus 10 points, or 22 points, and has a new rating of 1342, while player A loses 22 points and has a new rating of 1428.

If the game is drawn, then player A “gains” 16 minus 22 points, i.e. he loses 6 points, and his new rating is 1444, while player B gains 16 minus 10 points, or 6 points, and has a new rating of 1326.
If, as it usually happens, a player has many results in the same issue of King’s Korner, then the gains and losses are all computed based on the previous ratings, and then all gains and losses are combined into one for the rating change from one list to the next.

In situations where a player is provisionally rated, the rating adjustment is handled differently.  The games of provisionally rated players are held in a storage file until they achieve 10 results against players with established ratings.  At that time, a pseudorating (for purposes of the formulae only) is assigned based on their score in those 10 games and the ratings of their opponents, and then those 10 games are rated using the formulae above in the ordinary way.

Thus, the first rating published for a player is neither their provisional rating assigned for tournament qualification purposes (which is never used in the rating system), nor their pseudorating based on a self-consistency calculation for their 10-game performance and their opponents’ ratings, but rather it is the result of updating the pseudorating using the ordinary ratings update formulae and the 10 (or more) games that have been held for their initial rating.