From the New York Times’ Alan Schwartz :

A coming paper by a University of Pennsylvania professor and a Cornell University graduate student says that, during the 13 seasons from 1991 through 2004, white NBA referees called fouls at a greater rate against black players than against white players.

Justin Wolfers, an assistant professor of business and public policy at the Wharton School, and Joseph Price, a Cornell graduate student in economics, found a corresponding bias in which black officials called fouls more frequently against white players, though that tendency was not as strong. They went on to claim that the different rates at which fouls are called œis large enough that the probability of a team winning is noticeably affected by the racial composition of the refereeing crew assigned to the game.

N.B.A. Commissioner David Stern said in a telephone interview that the league saw a draft copy of the paper last year, and was moved to do its own study this March using its own database of foul calls, which specifies which official called which foul.

œWe think our cut at the data is more powerful, more robust, and demonstrates that there is no bias, Mr. Stern said.

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. The N.B.A. denied a request for its underlying data, even with names of officials and players removed, because it feared that the league™s confidentiality agreement with referees could be violated if the identities were determined through box scores.

The three experts who examined the Wolfers-Price paper and the N.B.A.™s materials were Ian Ayres of Yale Law School, the author of œPervasive Prejudice? and an expert in testing for how subtle racial bias, also known as implicit association, appears in interactions ranging from the setting of bail amounts to the tipping of taxi drivers; David Berri of California State University-Bakersfield, the author of œThe Wages of Wins, which analyzes sports issues using statistics; and Larry Katz of Harvard University, the senior editor of the Quarterly Journal of Economics.

œI would be more surprised if it didn™t exist, Mr. Ayres said of an implicit association bias in the N.B.A. œThere™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.

Mr. Berri added: œIt™s not about basketball ” it™s about what happens in the world. This is just the nature of decision-making, and when you have an evaluation team that™s so different from those being evaluated. Given that your league is mostly African-American, maybe you should have more African-American referees ” for the same reason that you don™t want mostly white police forces in primarily black neighborhoods.

This is the second time in a little more than a year the Times has cited Wolfers’ research — in March of ’06, The Gray Lady noted his claims that point shaving occurs in roughly one out of every 20 college basketball games.