Thursday, May 03, 2007
"This is not a view that one set of people hates another set of people. This is implicit, unconscious biases," said Wolfers, who conducted the study with Joseph Price, a graduate student in economics at Cornell.
"You see two players [collide] on the floor and you have to call a block or a charge. Does the skin color of the players somehow shape how you interpret the signals your brain gives you?"
Some economists on the private sports economics list dismiss the study as not being real economics. And true, there is no model in the paper that explains how it is referees would hold these unconscious biases. As I argued yesterday, it could be a style-of-play preference, something that can be influenced by how one calls fouls.
Steven Levitt raises another point that the size of these effects are not very large. He points to John Hollinger's calculation (subscribers link for ESPN Insider members) that the effect on Lebron James' total fouls if all his games were called by all-white officiating crews versus all-black crews would be 11 additional fouls over a season. His scoring average would be 0.3 points per game lower. Levitt doesn't mention another style of play factor that Hollinger picks up:
While we're talking about this study, one other item in it drew my attention: the finding that during the 13-year study period, teams with the greater share of playing time by black players won 48.6 percent of games. The authors seemed to imply some kind of mild institutional racism against black players by this result.
In fact, there's a much more obvious explanation -- the league imported a bunch of talent from Europe during the study period, almost all of it white, and the poorly run teams were the last ones to figure out there were good players on other continents. Thus, by default they ended up with more black players on their rosters.
And the poorer teams may commit more fouls as they play from behind; does this change the results? The study corrects for game effects which include the score, but I don't think I saw that it held constant the relative position of teams contesting for playoff spots, etc.
That doesn't make the Wolfers and Price paper incorrect. But I still would argue for additional tests to see if the age of the referee group matters (perhaps easily told, as far as I've been told, since each referee gets the next highest number on their jersey as they enter the league.) Rather than say this is evidence of bias, I'd look at their results and say "that is odd, doesn't really fit theory, what do you suppose explains that?" In statistical terms, the null hypothesis ALWAYS has to be "no discrimination" and rejecting the null doesn't mean you can accept the alternative.
UPDATE: Brian Goff makes some similar points.
UPDATE2: Phil Miller was inspiration for some of my comments, and he's greatly expanded on them here.