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NBA referees are biased

Mar 7, 2010, 11:08 AM EDT

Yes, NBA referees favor stars and swallow their whistles late in games.

That has been the conventional wisdom from fans for years, with the NBA of course denying that. But that is the beauty of the MIT Sloan Sports Analytics Conference — those “geeks” that fans deride for their fancy stats (“You can’t measure heart, man!”) can turn their attention and math skills on to issues like the refs.

And prove the fans were right. Kevin Arnovitz (and Henry Abbott) from TrueHoop is there (with fantastic coverage of the entire fascinating event) and breaks it down:

The study compared how likely officials were to call loose ball fouls on stars compared to non-star NBA players they were contesting in loose ball foul situations. The results were found over a three-year study in which 1.5 million plays were examined in 3,500 plus games. “Star” criteria was based on players’ MVP votes. The results: 42 percent of loose balls fouls called on stars in “regular” situation compared to 57 percent of the time on non-stars in plays. The numbers show a much more dramatic shift, favoring the star players when they are in “foul” trouble with only 28 percent of foul calls being called on them, a huge drop from the earlier 42 percent.

The other study involving the NBA involved a look at subjective calls (offensive fouls, traveling, double dribble, etc.) being made compared to non-subjective calls (kick ball, 24-second violation, etc.) over the course of the game. The tendency to want to let the players decide the game in close as well as late game situations showed itself once again in the form of omission bias, with the rate of calls falling dramatically from the first half to the second half. Another even sharper drop in subjective calls was apparent in overtime games with the subjective or “judgment” calls. The non-subjective call rates remained very level over those time spans.

Hey fans — the math guys are not just good at proving that the refs have issues. Those advanced stats you deride, they are right most of the time, too. Just a little something to think about.

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