Guest post: Don Coffin on golf performance measures
(This is Phil. In response to a previous post on golf scores, Don Coffin, an economist and sabermetrician from Indiana University Northwest, did a little extra research. Here's Don:)
I [Don] have done some research on the relationship between various measures of golfer performance and overall performance (strokes per round; prize money), but have found it difficult to know exactly where to go with it. Here’s how I have approached it.
Overall performance, measured as strokes per round, has three components:
1. Shots off the tee. There is essentially no variation in this measure of performance. Everyone has essentially one tee shot per hole, or 18 per round, and the standard deviation is almost zero.
2. Putts. There is some variation here, but less than one would expect. In 2007, according to data at PGATour.com, the average number of putts per round (averaged across golfers, so this is an average of averages) was 29.30, with a standard deviation on 0.52. The coefficient of variation was 1.77%.
3. All other shots. There’s a very little more variation here; again, using 2007 data, the average was 23.98 “other” shots per round, with a standard deviation of 0.63, and a coefficient of variation of 2.62%.
Overall, golfers in 2007 averaged 71.28 strokes per round, with a standard deviation of 0.59 strokes per round, for a coefficient of variation of only 0.83%. Overall performance was, then, less variable than the components of scoring with some variation.
The PGA reports a number of what it calls “skill statistics;” all of these are reported in Table 1. (Putts per round shows up in the “skill statistics;” “Other Shots” is Strokes per Round, minus Putts per Round, minus 18). If our objective is to explain overall performance, as measured by Strokes per Round, then we have to select explanatory variables from among the available performance measures. For 2007, the PGA reported all the “skill statistics” data for 196 golfers.
I believe it is inappropriate to use Putts per Round as an explanatory variable. If we could control adequately for other performance measures, then the (expected) coefficient on Putts (in a multiple regression) would be 1—each additional putt would raise Strokes per Round by 1. What would be useful, however, would be to find explanatory factors for the components of Strokes per Round—Putts, and Other Shots.
( ... continued)