ELO Rater
Rating Systems
USCF Rating System:
Details about the USCF rating system has been given by Prof. Mark E. Glickman of Boston University on his web pages at http://math.bu.edu/people/mg/uscf/rs/rs2.html
The initial 'provisional rating' period during the first 20 games is implemented as well as the rating floors as specified by USCF rules. The only deviation from the standard USCF rating system is the refusla to implement the 'event' logic.
The event logic allows the entry of many games to be processed at one time. This logic uses an averaging mechanism because the order of the games is lost in the reporting process. This averaging mechanism causes a slight loss of integrity in the final result. This loss of integrity has been deemed acceptable for the USCF because the burden of single game processing, both on the computaional resources, and on the tournament directors to provide the data, are cost prohibitive. Furthermore, one can argue that in a large group, the dynamics of the large group in a statistical sense will cause the errors to become self correcting. With a statistically small sample of players, a few dozen, which is the size of most clubs and groups, the loss of integrity of the event logic may not be self correcting. Also in a small gourp, the bourden of single entry is not too large. For these reasons, this program forces single entry fo games, providing the most acurate rating possible with small gorups.
Harkness System:
The table below shows the harkness system implemented by the program.
| Opponnent Rating Difference |
If High Wins Add to Winner and Deduct from Loser |
If Low Wins Add to Winner and Deduct from Loser |
If a Draw Add to Low and Deduct from High |
| 0 to 24 | 16 | 16 | 0 |
| 25 to 49 | 15 | 17 | 1 |
| 50 to 74 | 14 | 18 | 2 |
| 75 to 99 | 13 | 19 | 3 |
| 100 to 124 | 12 | 20 | 4 |
| 125 to 149 | 11 | 21 | 5 |
| 150 to 174 | 10 | 22 | 6 |
| 175 to 199 | 9 | 23 | 7 |
| 200 to 224 | 8 | 24 | 8 |
| 225 to 249 | 7 | 25 | 9 |
| 250 to 274 | 6 | 26 | 10 |
| 275 to 299 | 5 | 27 | 11 |
| 300 or more | 4 | 28 | 12 |