Yu-Sung and Jeff pointed me to a study by Joseph Price and Justin Wolfers on racial discrimination among NBA referees. Basically, black refs call more fouls on white players and vice-versa.
The NBA provides an intriguing place to test for taste-based discrimination: referees and players are involved in repeated interactions in a high-pressure setting with referees making the type of split-second decisions that might allow implicit racial biases to become evident. Moreover, the referees receive constant monitoring, and feedback on their performance. (Commissioner Stern has claimed that NBA referees “are the most ranked, rated, reviewed, statistically analyzed and mentored group of employees of any company in any place in the world.”) The essentially arbitrary assignment of refereeing crews to basketball games, and the number of repeated interactions allow us to convincingly test for own-race preferences. We find that—even conditioning on player and referee fixed effects (and specific game fixed effects)—that more personal fouls are awarded against players when they are officiated by an opposite-race officiating crew than when officiated by an own-race refereeing crew. These biases are sufficiently large that we find appreciable differences in whether predominantly black teams are more likely to win or lose, according to the racial composition of the refereeing crew.
The estimated difference is 0.2 fouls per player on the court per game, which comes to 1 foul per game for a team with all black players. Also, teams give black players less playing time (on average) when the refs are white–this looks like it hurt them more than the foul calls.
Looking at the raw data, white players commit lots more fouls per minute than blacks, but much of this can be explained by whites being more likely to be centers (presumably a more physical position with fouls as part of the job) and benchwarmers. Which reminds me that the data show a familiar pattern also noted in historical baseball data by Bill James: the black players are, by most measures, better than the whites (more points scored, more points per minute, more minutes played, more likely to be starters), which is consistent with discrimination in hiring (picking good-but-not-great whites over good-but-not-great blacks).
Other comments: yes, I would replace all the tables by graphs. (Start with Table 1–that’s an easy time series plot. Table 2 could be shown in a way similar to the graph in page 202 of our new book. Etc.) Figure 2 wold be better without those ugly horizontal lines at the top and bottom of the error bars.
Finally, black referees call more fouls than white refs–lots more for white players, but slightly more for black players too. Price and Wolfers characterize this as bias in judging white players but not in judging black players, but another interpretation is that black referees are just tougher about calling fouls in general.
P.S. Wolfers is the coauthor of this excellent review article on the deterrent effect of the death penalty.
P.P.S. In case it wasn’t clear, I like the paper.
One more thing
The analysis leading to Figure 2 should be replaced by a multilevel model. Really. These standard errors are huge, a clear case for partial pooling! No question. Take a look: