Umpires show ethnic bias in ball/strike calls—unless they're feeling watched

The talk of a post racial America seems to have died down, thankfully. Don't think for a second that race doesn't matter in America.

Ars Technica reports on an interesting study published recently by American Economic Review that backs up many previous studies, this one an analysis of millions of ball/strike calls by Major League umpires. It's yet another study that suggests we all try to do the right thing, but especially when we know someone is watching. Analysis of almost 2 million ball/strike calls shows umpires tend to favor pitches from their own ethnic group in games not monitored by computer ball/strike tracking...

There's a lot of behavioral literature that indicates we tend to like people who we think belong to the same group as us, and behave favorably towards them—even though we're not aware of doing so. Another, unrelated set of research indicates that we're all prone to behaving better if we think someone's watching us
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when an umpire was from the same ethnic group as the pitcher, they were more likely to call a pitch a strike, at least at a ball park that was not equipped with a QuesTec monitor. When the same analysis was performed at a QuesTec game, the probability that a pitch would be called a strike when there was matching pitcher/ump ethnicity dropped by a full percent—"more than offsetting the favoritism shown by umpires when QuesTec does not monitor them."
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"A black pitcher throwing a nonterminal pitch in the early innings of poorly attended games in a non-QuesTec ballpark gains over 6 percentage points by matching [the umpire's ethnicity] (41.4 versus 35.2 percent called strikes)."
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minority pitchers tend to have fewer pitches called as strikes even by umpires from the same ethnic group, and this effect is actually enhanced by QuesTec monitoring.
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Perhaps more significantly, the authors also compare game statistics for matching player/ump combinations in unmonitored ballparks. Here, the numbers are very consistent. For both white and minority pitchers, winning percentages went up by about five percent. Everything else—the number of hits and runs scored against them, the walks they gave up, and the number of home runs hit—all went down (so did strikeouts, although the effect was very small).

The study also presents data which suggests pitchers and batters are aware of these subtle biases, if only subconsciously. Pitchers pitch to certain areas around the plate and batters avoid swinging at certain pitches based on where they can get the maximum statistical benefit of the bias. Interesting stuff. Baseball has always centered on the "I know that you know that I know that you know," battle between hitters and pitchers. This suggests a new dimension to the old struggle.