Implicit Bias in the NBA

Posted on May 2, 2007 by


If sports didn’t exist, sports would have to be invented by social scientists.

Research in the social sciences is difficult since we do not often have data on worker productivity or data generated in a controlled environment. In sports, we have an abundance of data on worker productivity and the contest environment is much more controlled. Consequently, sports are a wonderful place to investigate human behavior.

The latest example of this wonder has been exhibited in today’s New York Times. Alan Schwarz penned an article entitled “Study of N.B.A. Sees Racial Bias in Calling Fouls.”

The study in question is co-authored by Joe Price and Justin Wolfers (you may remember that Wolfers was the author of a study of point shaving in the NCAA). The Price-Wolfers study – entitled “Racial Discrimination Among NBA Referees” – finds 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.

In writing his article, Schwarz called upon three outside “experts.” As Schwartz reports: Three independent experts asked by The Times to examine the Wolfers-Price paper and materials released by the N.B.A. said they considered the Wolfers-Price argument far more sound.

These experts were Larry Katz (Professor of Economics at Harvard and editor of the Quarterly Journal of Economics), Ian Ayres (Professor at Yale and author of more books and articles than I can count, including work in this specific area), and Dave Berri (some guy from California State). So maybe it was only 2.2 experts.

It is important to emphasize that Schwarz did not write this article last night on the back of a napkin. He began talking to the three of us a few weeks ago. We all reviewed the Price-Wolfers paper and the study by the NBA and we stand by the statement made by Schwarz in the article.

What Does this Mean?

It is also important to emphasize the story the article is telling. This is not about the NBA. It is about implicit biases in decision-making. I think the reaction Professor Ayres had to the study captures where the Price-Wolfers study falls in the literature:

“I would be more surprised if it didn’t exist,” Mr. Ayres said of an implicit association bias in the N.B.A. “There’s a growing consensus that a large proportion of racialized decisions is not driven by any conscious race discrimination, but that it is often just driven by unconscious, or subconscious, attitudes. When you force people to make snap decisions, they often can’t keep themselves from subconsciously treating blacks different than whites, men different from women.”

In sum, I do not think the Price-Wolfers study tells us that NBA referees are racists, or at least, they are not any more racist than anyone else. What it does tell us is that implicit biases exist and these biases can impact people’s decision-making.

The Value of Sports Economics

And of course this study once again highlights the value of sports economics. Ultimately we are not studying the value of a rebound or how best to evaluate an NFL quarterback. What we are doing is looking – as economists and social scientists – at how people process information and make decisions. I would argue that sports data makes such studies easier, certainly more fun, and also more informative. And hopefully, the work of Price and Wolfers will encourage more brilliant people to join the fun.

– DJ