Re: Formulas For Computer Rankings?
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.