The Official World Golf Rankings is very important in golf. They are used to rank PGA tour player performance. Unlike other sport rankings, like for example, the Fifa World rankings, the top 50 golfers in the rankings are granted automatic entry into the Major tournaments. And the top golfer in the rankings is regarded as the official best golfer in the world.
The rankings are endorsed by the six professional tours, which make up the International Federation of PGA Tours. Those are the PGA Tour, European Tour, Asian Tour, PGA Tour of Australasia, the Japan Golf Tour, and the Sunshine Tour.
Their calculation's isn't exactly straight forward. Points are awarded for players finishing in the prize positions for each of the qualifying tours. A minimum number of points are available for each tour. For example, the PGA tour is given minimum 24 points. The PGA Tour of Australasia also adopts the same minimum points tally.
Rankings points for the PGA Tour events are based on the strength of the top-200 hundred-ranked Tour players in the field. This, along with the top 30 ranked home field players in the tournaments. The exception is the Major tournaments, which are rated separately.
So, a minimum and maximum number of points are awarded for the prize positions - straight forward enough. Each tour player's position in the rankings is based on the ranking points he has obtained over a 2 year period. They are scaled down and then reduced in weekly increments to allow for current form.
Adjusted points are then totalled and an average calculated based on number of total points divided by the number of qualifying tournaments played in. Resulting averages are put into descending order with the highest average being the Worlds top ranked player.
That player, currently is Tiger Woods with a point's average of 20.73. This average puts him clearly above second place Phil Mickelson with 9.94, whom himself also has almost a double average over 3rd ranked Geoff Ogilvy with 5.66. After that, the rankings are much closer between the remainder of the current top 10. These rankings, are of course, only accurate at the time of writing.
The way these rankings are calculated puts the emphasis on average performance levels in these tournaments. There have been moments when they have been called into question, but the basis for their calculation is widely accepted, albeit sometimes altered, due to their endorsement.
The record recorded average for the World rankings is 32.44 over 45 events. Tiger Woods set this in 2001.
The rankings have been chopped and changed in golf's history. And subsequent changes might well occur in the future. However, as of 2008, that is how PGA tour player rankings are calculated.