Why Economists Shouldn't Study Sports (By Themselves)

Kevin Hassett, an economist at AEI and an adviser to John McCain, is stepping into the debate over whether NBA referees are fixing games (via Marginal Revolution). Having an economist apply his statistical tools to sports data is a dicey proposition because even after applying his tools, the economist has to properly interpret the results. That generally entails exploring alternative explanations for the results, and economists as a group probably aren't well suited for this. A case-in-point is Hassett's piece on Bloomberg describing his findings:

A first look at the numbers is troubling. Basketball is the one sport that should have the smallest home-field advantage. Every court is the same. Yet in the 2008 playoffs, the home team won 64 of 86 games -- or 74 percent of the time. If we exclude the first round, where there are bound to be some blowouts, the home team won 34 out of 42, an 81 percent clip.
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Travel might explain a modest home-court advantage. It could also be that adrenaline is stoked by the fans, and the pattern is completely innocent. There may be another answer.

Obviously, you're not a golfer. Just because all the rims are 10 feet off the ground and all the free-throw lines stand at 15 feet doesn't mean that "[e]very court is the same." It's about knowing exactly where you are on the court at all times, without having to think about it. Players have to know, without looking at the basket, exactly how far they are from the basket. When a shooter is running off a double-screen, he has to have an innate feel for when he's behind the three-point line. These kinds of things are tremendously important, especially at the NBA level.

Hassett also thinks he has stumbled upon something when he discovers that home-court advantage is more pronounced in the playoffs than in the regular season. He thinks this is important because playoff games should be no different from regular season games. But anyone who has played in a post-season game at any level knows that playoff games are completely different from regular season games. Everyone plays tighter, inexperienced shooters get a bit more hesitant, etc. Also, coaching strategy changes dramatically. I suspect that if you told an NBA fan that home-court advantage was more pronounced in the playoffs than in the regular season, the fan would say, "of course it is."

To be fair to Hassett, he correctly identified one of the biggest (and most under-appreciated) reasons for a home-court advantage in basketball: the fans. But he definitely should have consulted a basketball analyst or an NBA player before interpreting the data.