STEVE INSKEEP, HOST:
This next story begins with a mistake, something just short of perfection. In 2010, Detroit Tigers pitcher Armando Galarraga nearly threw a perfect game. A perfect game in baseball, of course, means you go through nine innings, three outs in each inning, and nobody gets on base - 27 outs in a row. Galarraga got 26. And then the final batter hits a little ground ball. He's running toward first base. This is a little hard to watch. The first baseman tosses the ball over to get him out.
(SOUNDBITE OF ARCHIVED RECORDING)
UNIDENTIFIED UMPIRE #1: Oh, he's safe.
INSKEEP: And the umpire called him safe.
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UNIDENTIFIED UMPIRE #1: He is safe.
INSKEEP: No perfect game. Even though the replay shows again and again and again the batter was out. The umpire later admitted his mistake. Other umpires surely think about mistakes. And new social science research tells us that the fear of blowing big calls may affect how umpires do their jobs. NPR's Shankar Vedantam regularly brings us social science research. He's with us once again. Hi, Shankar.
SHANKAR VEDANTAM, BYLINE: Hi, Steve.
INSKEEP: So what are the umpires doing?
VEDANTAM: Well, the umpires really, really, really want to avoid the kind of mistake that the umpire made in this game in 2010. A couple of Stanford Business School Ph.D. students - Etan Green and David Daniels - they've just finished analyzing more than a million pitches thrown in professional baseball. And they find that when it comes to calling balls and strikes - so one particular domain of umpiring - umpires are really reluctant to make calls that invite criticism. Here's Green.
ETAN GREEN: If you're an umpire and you're unsure about what the correct call is and you're given a choice between one call that's particularly consequential and one call that's relatively inconsequential, they will more or less preserve the status quo. Well, if you want to avoid the - say, the public criticism that is associated with making a pivotal call an error, then you may err on the side of preserving the status quo.
INSKEEP: OK. So we're talking about balls and strikes here, whether the ball's over the plate. And we're talking about biases, but not bias toward or against a team - for the Giants or for the Royals or whatever. We're talking about some other kind of bias. And they're going for the status quo? What does that mean exactly?
VEDANTAM: Well, so basically umpires are reluctant to make calls that can flip the outcome of the game, change the status quo and have them be responsible for whether the game tips one way or the other. So if calling a strike can tip the game one way, they're more likely to call a ball. If calling a ball can reverse the momentum in the game, they're more likely to call a strike. Green and Daniels also find, interestingly, that the higher the profile of the game - the larger the TV audience - the greater the bias because the umpires are thinking - maybe consciously, maybe unconsciously - millions of people are watching me, I hope to God I don't blow it.
INSKEEP: I'm just thinking through the scenarios here. Bases are loaded. There's already three balls, one more ball would walk in a run that might win the game. The umpire's more likely to call a strike in that situation.
INSKEEP: Let's assume this is true. Basically, we're saying the umpires are avoiding criticism. They're going for the safe choice. Are they rewarded by Major League Baseball, which selects the umpires, for making safe choices?
VEDANTAM: Well, it turns out that Major League Baseball seems to have its own biases. When Green and Daniels analyzed which umpires get selected to officiate big games, it turns out the league tends to pick umpires who are not the most accurate, but umpires who tend to be the most consistent in their calls. Here's Green again.
GREEN: Baseball umpires are allowed to systematically deviate from the official strike zone as long as they maintain a consistent strike zone of their own.
INSKEEP: We better remind people that what the strike zone is can be hard to figure out.
VEDANTAM: It can be hard to figure out, but I think what's happening here is that Major League Baseball is using consistency presumably as a proxy for accuracy because if the umpire makes the same call over and over again, it could be because Major League Baseball thinks the umpire is being accurate. At the very minimum, of course, being consistent is at least being fair. So if you make the same calls the same way for all teams, presumably you're being fair.
INSKEEP: Shankar, thanks very much.
VEDANTAM: Thank you, Steve.
INSKEEP: That's NPR's Shankar Vedantam. Now, however the umpire precisely was measuring the strike zone last night, Madison Bumgarner found it in Game 5 of the World Series. The Giants pitcher turned in a dazzling performance. He shut out the Kansas City Royals, 5-nothing. His team is within one victory of the title as the series returns to Kansas City. Transcript provided by NPR, Copyright NPR.