Do golfers give less effort when they're playing against Tiger?
According to this golf study by Jennifer Brown, the best professional golfers don't play as well in tournaments in which they're competing against Tiger Woods. Apparently, they have a pretty good idea that they won't beat Tiger, and so they somehow don't try as hard.
Brown ran a regression to predict a golfer's tournament scores. She considered course length, whether Tiger was playing, whether the golfer was "exempt" (golfers who were high achievers in the past are granted exemptions) or not, whether the event was a major, and so forth. It turned out that when Tiger was playing, the exempt golfers' scores were about 0.8 strokes higher (over 72 holes) than when Tiger sat the week out. Non-exempt golfers, on the other hand, were much less affected by Tiger's participation – only 0.3 strokes. Brown suggests that the difference is that the non-exempt golfers know they can't beat Tiger anyway, so his presence doesn't deter them from playing their best.
Also, when Tiger was on a hot streak – his scores in the previous month were much better than other exempt golfers – the effect increases. Now, instead of being just 0.8 strokes worse than usual, the exempt golfers are 1.8 strokes worse. During a Tiger "slump," the exempt golfers are so pumped by their chance of winning that they're *better* than usual, instead of worse – by 0.4 strokes.
The result seems reasonable – the less chance you have of winning, the less effort you give. But 0.8 strokes seems like a lot. That's especially true when you consider that it's not *every* time that Tiger Woods runs away with the lead. It might be 0 strokes when Tiger is struggling, but 1.6 strokes when it's obvious that it's a lost cause this week. And how does Phil Mickelson lower his scores by 0.8 just by trying harder? Is it more practice? Is it setting up better? Is it spending more time reading the green? What actually is it?
(UPDATE: a couple of commenters noted that with Tiger in the field, certain opponents might change their style of play to take more risks to beat him, and that might cause the scoring difference. However, the study checked for that, by looking at the 72 individual holes, and it found no difference in the variance based on whether or not Tiger was playing.)
There's something else that's confusing me, and that's one of the actual regression results in the paper. Brown has a dummy variable for (among other things) every player, every golf course, and whether or not the tournament is a major. The coefficient for the major is huge: around 17 strokes.
That doesn't make sense to me, because that's after adjusting for the player and the course. It says that if Phil Mickelson plays Pinehurst #2 twice, with the same course length and the same wind and temperature, but one time he's playing a major and the other he's not, *his score will be 17 strokes higher in the major*. That just doesn't sound right to me. Why does calling a tournament a "major" make every golfer 17 strokes worse? (See tables 4 and 5 of the study.)
(Also, how can you divorce the course from the major? As far as I know, the Augusta National Golf Club, which hosts the Masters (a major), doesn't host any other PGA tournaments. So what happens when you run the regression, and the Augusta dummy is always the same as the Masters dummy? I'm not an expert after my one course – but doesn't that cause some kind of matrix problem in the regression?)
I wouldn't even expect a coefficient of +17 only if you didn't adjust for the course at all. Well, maybe if you look at last year's Masters. At Augusta in 2007, every golfer finished over par. But in the 2008 Buick Invitational (which is not a major), 34 players finished at or below par, and the winner (Tiger) was at –19.
But that's an exception. Eyeballing the four majors on Wikipedia, the Masters and PGA Championship usually feature a winner around –8. The British Open looks a little easier, and the US Open a little tougher. Eyeballing the non-majors in 2007, the typical winning score looks to be somewhere in the mid-teens.
So the difference is probably around 7 strokes or so. After correcting for the higher caliber of golfer in the majors, you might get to, what, 12 or 13? You're still short of the 17 the regression found. And, again – that's BEFORE adjusting for the difficulty of the course! So I just don't understand.
What's going on here? Am I figuring something wrong?
Hat Tip: The Sports Economist