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Study finds biases

Number of fouls affected by race

NBA commissioner David Stern sees no bias in refs. (LAWRENCE JACKSON/ASSOCIATED PRESS)

An academic study of the NBA suggests that a racial bias has existed on the basketball court.

A forthcoming paper by a University of Pennsylvania professor and Cornell University graduate student says that, during the 13 seasons from 1991 through 2004, white 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 smaller.

They went on to claim that the different rates at which fouls are called "is large enough that the probability of a team winning is noticeably affected by the racial composition of the refereeing crew assigned to the game."

NBA commissioner David Stern said in a telephone interview that the league saw a draft copy of the paper late last year, and was moved to conduct a study in March using its own database of foul calls, which specifies which official called which foul. "We think our cut at the data is more powerful, more robust, and demonstrates that there is no bias," Stern said.

To investigate whether such bias has existed in sports, Wolfers and Price examined data from box scores. They accounted for factors such as players' positions, playing time, and All-Star status; each group's time on the court (black players played 83 percent of minutes, while 68 percent of officials were white); calls at home games and on the road; and other relevant data.

But they said they continued to find the same phenomenon: that players who were similar in all ways except skin color drew foul calls at a rate difference of up to 4 1/2 percent depending on the racial composition of an NBA game's three-person referee crew.

Three independent experts asked by The Times to examine the Wolfers-Price paper and materials released by the NBA said they considered the Wolfers-Price argument far more sound.

The paper by Wolfers and Price has yet to undergo formal peer review before publication in an economic journal, but several prominent academic economists said it would contribute to the growing literature regarding subconscious racism in the workplace and elsewhere, such as in searches by police.

"I would be more surprised if [an implicit association bias in the NBA] didn't exist," said Ian Ayres of Yale Law School, one of the independent experts. "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."

Another expert, David Berri of California State University-Bakersfield, added: "It's not about basketball -- it's about what happens in the world."