Baseball: Possibly Less Racist Than You Thought

A few years ago economist Daniel Hamermesh made a splash with a study purporting to show that MLB umpires were biased toward players of their own race when calling balls and strikes. Now the University of San Francisco’s Jeff Hamrick has a new study that examines data over a longer timer period (1989-2010 vs. 2004-2006) and finds that there is little evidence of racial bias.

We investigate potential racial bias by Major League Baseball umpires. We do so in the context of the subjective decision as to whether a pitch is called a strike or a ball, using data from the 1989-2010 seasons. We find limited, and sometimes contradictory, evidence that umpires unduly favor or unjustly discriminate against players based on their race. Potential mitigating variables such as attendance, terminal pitch, the absolute score differential, and the presence of monitoring systems do not consistently interact with umpire/pitcher and umpire/hitter racial combinations. Most evidence that would first appear to support racially connected behaviors by umpires appears to vanish in three-way interaction models. Overall, our findings fall well short of convincing evidence for racial bias.

I assume future research will investigate what we’re all dying to know: Whether or not there is racial bias in fielder obstruction calls.



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