Racial bias in the NBA refereeing?

A study outlined in the New York Times today has found evidence of racial bias in the way referees call fouls. Over 13 seasons, the study found that white referees called fouls against black players at a greater rate than against white players.

After accounting for a large number of factors, which are outlined in the article, it was found that:

"We find that black players receive around 0.12-0.20 more fouls per 48 minutes played (an increase of 2.5-4.5 percent) when the number of white referees officiating a game increases from zero to three."

The NBA disagrees of course, stating that it's own study found no evidence of bias. The NBA's study was less formal and academic, and also didn't adjust for the various factors such as position and veteran status as the original article.

From Freakonomics