From an article of the same title by Alan Schwarz in the NY Times:
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 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 "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." 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. "We 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.
"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."
I buy that last explanation...that people, regardless of the intentions, have natural and often sub-conscious bias against people that are different from them...and that bias can easily come out under stress or when there isn't time to think better. I see it in myself when I react differently to people of different color...until I consciously remind myself that I can't assume something about someone based on the color of their skin. I see it when Christians are more eager to attack people who are different from them (like homosexuals) while basically ignoring others that they can relate to (like gluttony, gossip, materialism, etc). I think racism is still a problem and that black people are just likely to be prejudiced against white people as the flip side. If you have the chance, watch the FX series "Black. White" (which I've mentioned before and before). This also reminds me of something else. A while back I set a season pass for Pistons games. I never watch them (until playoff time) but my six-year-old watched a bunch of them. He would tell me about the games and I got a kick out of when, for example, he called Billups "Mr. Big Shot." Anyway, we were watching part of a game together one day and he asked me, "Dad, why do so many basketball players have dark skin?" I wasn't exactly sure how to answer, but what else could I say except that the guys who play in the pros do so because they are taller and are better at jumping and putting the ball in the basket...and so these guys with dark skin must be better at those things. I also said that maybe they practiced more too. I didn't want to admit to him that black people and white people are different (in this admittedly narrow context of playing professional basketball), but it's so obvious and common-sensical that I couldn't help it.