NBA's debunking of referee bias flawed, says researcher

A couple of years ago, Joseph Price and Justin Wolfers came out with a study (.pdf) that found a bit of racial bias among NBA referees. The more white referees on the court, the more fouls were called against black players (relative to white players). And vice-versa: more black referees meant relatively more fouls against whites. (The vice-versa has to be true by definition, since the white referees can only be judged relative to their black peers.)

At the time, I summarized the Price/Wolfers study here, here, and here.

When that study came out, the NBA wasn't pleased, and David Stern commissioned a counter-study to refute it. I haven't seen that NBA study, but David Berri has, and he recently wrote about it on his blog. Apparently, it's very amateurish: according to Berri, the researchers estimated the results twice, once with a dummy variable for black refs, and again with a dummy variable for white refs. But, as Berri points out, that will just give the same results -- it doesn't matter which way you define the dummy variable, and "that suggests that the person doing the work for the NBA didn't understand dummy variables."

I wish I had a copy of the NBA study ... I haven't been able to find it online, and I think I read somewhere that it was only distributed to a select group of readers. One of them was Joseph Price, the author of the original study. Berri's post was based on a visit Price made to Berri's class. In addition to the dummy variable issue, Berri reports that Price said "that was just the beginning" of the problems with the NBA study, but gives no further details.

Anyone know where the NBA response can be found? I'd love to take a look at it firsthand.

P.S. Berri gets in a shot at non-academic researchers:

"Unfortunately, the quality of work offered by the consulting firm [the NBA hired] was consistent with what you sometimes see in on-line studies. In other words, it wasn’t very good. In fact, much of it consisted of mistakes you would not expect an undergraduate in econometrics to make."