Statistical Analysis Reveals Racial Biases in NBA

The New York Times reported on Wednesday on a peer-reviewed article by economics professors with a story called "Study of N.B.A. Sees Racial Bias in Calling Fouls." The research paper is entitled "Racial Discrimination Among NBA Referees" and was written by Joseph Price (Cornell) and Justin Wolfers (University of Pennsylvania). Samantha Cook, a recent Harvard Ph.D. in Statistics and a post-doc at Columbia, has a blog called Statistical Modeling, Causal Inference, and Social Science where she analyzes the Price and Wolfers paper (posts the abstract of the paper and has direct link to the paper's pdf that I have placed above):

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).

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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

Ms. Cook likes the paper and so does Mad Professah. I see it as an excellent example of mathematics and social justice, the topic of the conference I attended last week. One aspect of mathematics and social justice is the use of mathematics to highlight and understand issues of social justice, in this case the existence of race-based disparities in modern society.

This favorable opinion of the article has not been shared by the NBA, its players and many other commentators in the blogosphere and mainsteam media.