Are MLB Umpires Racially Biased?

Do major league umpires discriminate? Evidently, they do. Probably not intentionally, but the data suggest that they do. In a just published article in the American Economic Review ("Strike Three: Discrimination, Incentives, and Evaluation"), Christopher A. Parsons, Johan Sulaeman, Michael C. Yates, and Daniel S. Hamermesh, using data from the cameras the Major League Baseball installed in ballparks to track the location of every pitch (see my earlier post, "Are Baseball Umpires Biased"), found that umpires are more likely to call "strikes" "balls" if their ethnicity differs from the pitcher. They also found, however, that pitchers often pick up on this and adjust their pitching accordingly. Here's the abstract from the paper:

Major League Baseball umpires express their racial/ethnic preferences when they evaluate pitchers. Strikes are called less often if the umpire and pitcher do not match race/ethnicity, but mainly where there is little scrutiny of umpires. Pitchers understand the incentives and throw pitches that allow umpires less subjective judgment (e.g., fastballs over home plate) when they anticipate bias. These direct and indirect effects bias performance measures of minorities downward. The results suggest how discrimination alters discriminated groups’ behavior generally. They imply that biases in measured productivity must be accounted for in generating measures of wage discrimination.

No need to review the entire paper here. A short summary of it can be found at the Freakanomics blog ("Strike Three: Do MLB Umpires Express Racial Bias in Calling Balls and Strikes?"), while the actual paper can be found here: Strike Three: Discrimination, Incentives, and Evaluation.