SI Vault
Jim Lackritz
August 08, 2011
Most golfers think that employing a simple handicap evens the odds in any match. Most golfers are wrong
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August 08, 2011

Beating The System

Most golfers think that employing a simple handicap evens the odds in any match. Most golfers are wrong

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1. Rory McIlroy (10) 143 1
2. Luke Donald (5) 138 2
3. Lee Westwood 106 3
4. Charl Schwartzel 90 4
5. Steve Stricker 79 5
6. Martin Kaymer 64 6
7. Phil Mickelson 41 8
8. Nick Watney 33 10
9. Dustin Johnson 29 9
10. Jason Day 26

Bless the handicap system. It nourishes the $5 Nassau by allowing players of unequal ability to compete on an equal level. Or does it? I researched the handicap system recently (for an article in Chance, a journal of the American Statistical Association) and found that the system doesn't work as well as we assume.

A player's handicap index is calculated by taking the average of the best 10 of his 20 most recent rounds and multiplying it by 0.96. That's why most golfers only play to their index about 20% of the time and someone with an index of 15 has an average score of 90, not 87. That's also why golfers are almost never happy with their score.

If the system is working, then the chances of any player winning a match should be equal. Sure enough, my research showed that when the handicap difference is less than five strokes, each player wins approximately the same percentage of time. But when the difference is five or more strokes, the better golfer wins more often. For a 10 index versus a 15 index match, the 10 index wins almost 50% of the time, with more than 8% ties. As the index difference increases, the better player's chances increase. When the difference is 15 strokes or more, the better player wins or ties 62% to 73% of the time.

In addition, I simulated one-, two- and four-round tournaments composed of one golfer each with a zero, five, 10, 15, 20, 25 and 30 index. In a one-round tournament the zero- and five-handicap golfers each won about 18% of the time, while the 30 handicapper won only about 10% of the time. With a two-round tournament, winning percentages increased for the better golfers and decreased for the weaker ones. In a four-round tournament the scratch golfer won 28% of the time, while the 30 handicapper won only 6% of the time.

However, when all players compete in one flight, a higher handicap player will win more often. Why? Because there are more players with indexes between 15 and 30, and chances are one of them will shoot a score at the low end of his distribution.

What's the takeaway? To win more bets, play against weaker players. In your club events, if they are not flighted, chances are that a higher-handicap player will beat you. In a team format (better-ball, scramble, etc.) based on index scores, play with a higher-index player. And, as always, look out for sandbaggers.

Jim Lackritz is professor emeritus of management information systems at San Diego State.


[This article contains a table. Please see hardcopy of magazine or PDF.]

GOLF PLUS will next appear in the Aug. 22 SPORTS ILLUSTRATED.