Economists Find Racial Bias in NBA Refereeing

May 1, 2007

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A new academic paper by Justin Wolfers and Joseph Price finds evidence of subconscious racial bias by NBA referees, although the effects are rather small:

Mr. Wolfers and Mr. Price examined whether otherwise similar black and white players had fouls-per-minute rates that varied with the racial makeup of the refereeing crew.

“Across all of these specifications,” they write, “we find that black players receive around 0.12-0.20 more fouls per 48 minutes played (an increase of 2 ½-4 ½ percent) when the number of white referees officiating a game increases from zero to three.”

Mr. Wolfers and Mr. Price also report a statistically significant correlation with decreases in points, rebounds and assists, and a rise in turnovers, when players performed before primarily opposite-race officials.

“Player-performance appears to deteriorate at every margin when officiated by a larger fraction of opposite-race referees,” they write. The paper later notes no change in free-throw percentage. “We emphasize this result because this is the one on-court behavior that we expect to be unaffected by referee behavior.”

I’m not sure exactly what to make of their findings without having read the whole paper, but an effect of 0.12 fouls per 48 minutes translates into just 13 fouls over an entire season (assuming a player is on the court every minute of all 82 regular-season games); I don’t doubt the statistical significance of their results, but a foul every 8-9 games would only be an important effect if referees were non-randomly assigned and most games had either all-white or all-black officiating crews, but neither is the case (77% of NBA games were refereed by a mixed-race crew over the period studied, which is a figure likely to increase as the number of black NBA referees is increasing). In other words, we would expect these effects to by-and-large cancel themselves out over the length of a season, even if individual games might be slightly biased by these effects.

As the Times account indicates, the study is probably a more interesting contribution to the debate over the role of subconscious/unconscious racism than it is in terms of its insight into NBA refereeing–doubtless to the disappointment of frequent ref critics like Mavericks owner Mark Cuban.

10 responses to “Economists Find Racial Bias in NBA Refereeing”

James Joyner

May 2, 2007 at 7:46 am

I wonder if there are a handful of players skewing the data. I’m only a very casual follower of the NBA but can think of four or five players known for thuggish play. All of them are black.
carpeicthus

May 2, 2007 at 10:03 am

James: Read the data — they’re not measuring black v. white players, they’re measuring the same players with different referees. Sounds like a solid study, but I also agree with Chris’s conclusion.
Andy

May 2, 2007 at 12:27 pm

13 fouls over a season seems pretty significant. That’s two games fouled out.
Brainster

May 2, 2007 at 1:50 pm

I’m concerned at some of the adjustments reported. For example, they “adjust” for the fact that centers foul more often than other players and are disproportionately white. Translation: They reduced the number of fouls called on white guys. They adjust for the fact that all-stars get called for fouls less than non-stars. But all-stars are disproportionately black (nine of the ten selected starters this year were black and the tenth was Yaou Ming), so they increased the number of fouls by black guys. And what the heck did they mean when they adjusted for a players “assertiveness on the court”?
Chris Lawrence

May 2, 2007 at 1:57 pm

Well, it would be a big effect if some players always played before all same-race crews and some players always played before all opposite-race crews. But since they don’t, the substantive effects diminish quite a bit.

The more I think about it, the more I wonder about the effects of partial separation on their results; when you control for race, height, size, “star power,” years in the league, and position on the court, I’m not sure there are enough players in each “bucket” combination to make reliable inferences. Who’s the white equivalent of Shaq or the black equivalent of Dirk Nowitzki?

Race may also be functioning as a proxy for “playing style” here. Maybe white refs are slightly less tolerant of aggressive play, more associated with American players (predominantly black) than Europeans (almost all white), than black refs–perhaps an artifact of generational effects (I’d expect the average black ref is younger than the average white ref).
Bugz

May 2, 2007 at 5:01 pm

Is no one even willing to ask the question, “Do black NBA players actually commit more fouls?”

I don’t know if they do or not, but was the hypothesis even considered? Seems like maybe it should be considered, if only to eliminate the possibility, if nothing else.
David L

May 2, 2007 at 6:52 pm

Given that that authors of this supposed study can not say which official called what fouls, in the case of any mixed race crew, the study seems rather inconclusive.

Further, I skeptical of trying to judge human performance, and subjective opinion, based purely on box scores. Much to do about not much.
bill

May 7, 2007 at 4:16 pm

This study, the headlines and media reaction are yet another example of the insanity happening in this country when it comes to racism. The data from this exact same study found that: black players received fewer fouls per 48 minutes than white players, 4.33 to 4.97. The headlines should read WHITE PLAYERS RECEIVE 15% more fouls per game than black players due to racial bias. Read that again, white players recieve a half of a foul more per game than black players. Take this fact from the EXACT same study and create a headline that says there is racial bias towards black players. Huh??? How do you get that conclusion? WAKE UP PEOPLE!