How Well Should You Play?
By Dean Knuth

Does it seem to you that you play a few strokes over your Course Handicap most of the time? Well, that's normal under the USGA Handicap System.

Why? The USGA Handicap System is based upon the potential ability of a player rather than the average of all his scores. The USGA's Handicap Research Team tells us that the average player is expected to play to his Course Handicap or better only about 25 percent of the time, average three strokes higher than his Course Handicap, and have a best score in 20, which is only two strokes better than his Course Handicap.

A few words and a little arithmetic may explain. A player's Handicap Index reflects his potential because it is based upon his best scores posted for a given number of rounds, ideally the best 10 of his last 20 rounds. Since the USGA has his worst 10 scores tossed out, his Handicap Index reflects his best days.

The arithmetic comes in when the golf club calculates a player's Differential for each score he posts. The Differential is the difference between a player's adjusted gross score and the USGA Course Rating of the course on which the score was made, multiplied by 113, and then the total is divided by the USGA Slope Rating from the tees played rounded off to one decimal place.

For example, if you post an 80 on a course with a Course Rating of 68.7 and a Slope Rating of 105, your Handicap Differential is 12.2. The next step entails averaging your best Handicap Differentials, which your golf club or association then will multiply by a 96-percent "bonus for excellence" factor that slightly favors the lower-handicap player. The next step is to delete all numbers after the first decimal digit, with no rounding off to the nearest tenth. Your club Handicap Committee then reviews your record, modifies it, if necessary and then issues your USGA Handicap Index.

If you have a USGA Handicap Index of 11.6, for instance, it translates into a Course Handicap of 14 when you play from the middle tees one day at a course with a Course Rating of 72.1, with a Slope Rating of 135. So a little addition (72.1 + 14) leads you to think that you will consistently shoot around 86. In reality, your score average is normally three more strokes than that, or an 89. The USGA Handicap Research Team has determined that your best score in 20 is normally only two strokes better than your Course Handicap, or an 84; the probability of your recording an 83 twice in 20 rounds is only one in 50.

A good way to think of the range of scores upon which your USGA Handicap Index is based is the old bell curve that school teachers refer to when discussing the range of scores on an exam. The scores of most players, when plotted out, are distributed on a bell curve from the high to low end of the scale. Thus, when you drop out the worst half of your scores, the average of the remaining 10 scores on the upper part of the bell curve reflect your potential ability.

Now, once in a while you will hear about someone shooting an incredible tournament score, such as a net score of 59. What are the odds of shooting a score like that? These tables from the USGA's Handicap Research Team have figured the odds of one exceptional tournament score up to ten strokes better than the Course Handicap.

For example, the odds of our example player with a Course Handicap of 14 beating it by eight strokes (-8 net) once is 1,138 to one. Put another way, the average player posts 21 scores a year. That means that to score this well, assuming the Handicap Index is correct, would take 54 years of golf to do it once. The odds of a player beating his Course Handicap by eight strokes twice is only 14,912 to one. That's 710 years of golf for the average player -- odds far beyond the realm of reasonableness.

Since the USGA Handicap System is designed to promote fairness during competitions, what happens if a player's scores contradict the odds and he consistently plays better than his Handicap Index when some crystal or trophies are at stake? The USGA has created a Formula - we'll spare you all the complicated arithmetic - that is outlined in the USGA Handicap System manual under Section 10-3, "Reduction of a USGA Handicap Index Based on Exceptional Tournament Scores." A player's USGA Handicap Index will be automatically reduced when he records at least two tournament scores in a calendar year or in his latest 20 rounds that are a minimum of three strokes better than his USGA Handicap Index. The better the scores, the greater the reduction.

The end result is you've got your USGA Handicap Index for better or for worse. Don't worry if you never seem to play to it on a given day. All golfers are in the same boat because USGA Handicap Indexes are based on a player's potential ability rather than the average of his scores. 

(from www.usga.org)