View Full Version : Formulas For Computer Rankings?

Dec 9th, 2007, 08:29 PM
Does anyone know how the official rankings were formulated in the 70's and 80's? I would be very interested if anyone had any information on this subject

Dec 14th, 2007, 09:56 PM
Any help from you knowledgeable fans would be appreciated.

Dec 17th, 2007, 12:11 AM
Rankings were based on average points per tournament when I started following tennis around '83/'84. Don't know specific numbers but some of the concepts used were:

* A minimum divisor of 12 was used, so if you played < 12 events your total points were still divided by 12 to normalize the average totals. (So a player wouldn't be able to game the system by playing only the Grand Slam events then not any of the smaller events.)
* Players earned points for the rounds they reached in an event, as well as "quality" points based on the ranking of the opponents she beat. The WTA eliminated the quality points a few years ago.
* For a while, the computer used a system of diminishing returns, where the recent 6 months were weighted more than the prior 6 months. That's partially why Evert was able to recapture #1 from Navratilova after winning the '85 French - Evert had taken the last two majors ('84 Australian in Dec '84, and '85 French in June '85), and the points for her Slam titles were at full weight. Navratilova had the other two slams ('84 Wimbledon & US) but didn't have full weight for those events.

The WTA did away with the averaging system in the mid/late 90s. I believe it was to encourage players to play more - you can now continue to build your ranking points by playing more events. The downside of this is that all of a player's losses may not count against her if she plays more than 18 events (witness Bartoli has lost >30 times in '07, but still ranks among the top ten), and injuries may be more prevalent due to a player's overplaying.

Dec 17th, 2007, 10:16 PM
Thanks for the info Jack do you know any sources where I could find exact point totals

Calvin M.
Dec 19th, 2007, 01:19 AM
The minimum divisor was also how I remember the rankings being calculated. That method held up well into the 90's, if memory serves.

Dec 21st, 2007, 03:07 PM
Why did they change the ranking system if it worked so well?

Dec 21st, 2007, 03:08 PM
Also, Calvin M. welcome to the board!!

Calvin M.
Dec 21st, 2007, 10:39 PM
Why did they change the ranking system if it worked so well?

I am so sorry but I don't remember. Some time in the last 5 years the divisor was changed but I can't recall the details. Somebody here should know. I think the reason why I couldn't retain the rule change is because it became so convoluted.

Thank you for the welcome! Much appreciated!

Dec 27th, 2007, 05:11 PM
Why did they change the ranking system if it worked so well?

Simply put, the WTA wanted its top stars to play more often. Compared to her immediate predecessor at #1, Steffi Graf tended to play a fairly limited schedule even during her early years at the top of the women's game and she started to trim her schedule down even more when she started suffering from serious injuries. For instance, Navratilova and Evert played each other 12 times in 1983 and 1984 whereas Graf met Seles only once in all of 1996. I also suspect that the WTA found it a bit embarrassing that Graf was able to comfortably hold on to her #1 ranking in spite of playing only 11 events each in 1995 and 1996, which was below the minimum divisor in both years - 12 in 1995 and 14 in 1996.

As a result the WTA officials decided that switching to an additive ranking system made good business sense as they felt it would force the top players to play more often. They put the matter to a vote and the rank-and-file players mostly supported the move. The top players (Graf, Seles, Novotna) opposed the proposal and Graf went so far as to state that she wasn't going to play any more than she already was, no matter what ranking system the WTA used. Ultimately, I think this decision cost the WTA as it mostly resulted in more and more players suffering serious injuries due to overplaying and many more ranking controversies than had ever been under the old divisor.