Just in time for this year's major league baseball playoffs, Wharton professor Etan Green offers a fascinating interview about the subjective determinations baseball umpires make when calling balls and strikes.
The strike zone, ostensibly, is an objectively determined region "defined by the width of home plate on the ground and the batter’s stance." In a fully empirical world that is only guided by directly visible evidence, an umpire should always call a pitch that ends up in the same place the same thing. Once a ball, always a ball; once a strike, always a strike.
That's not what happens, as Green clearly shows. If a hitter is behind 0-2, a pitch that is actually a strike (as determined by the stereoscopic cameras behind home plate) may well be called a ball. If a hitter is up 3-0, the next pitch -- even if it is yet another ball --is more likely to be called a strike than the same exact pitch thrown earlier in the count. Umpires are human.
Learning about Green's work reminded me of a 2008 paper I wrote, "Friendly Skepticism About Evidence Based Library and Information Practice." While there are obvious merits to using valid data to inform library decision-making (such as downloads or check-out statistics), librarianship is just as much a human enterprise as is baseball umpiring. And as such librarianship is just as subject to capricious factors, such as the will of a powerful faculty member to influence collection decisions regardless of the data that clearly shows a new acquisition would be a poor use of funds.
So I maintain my"friendly skepticism" about the evidence-based imperative. Let's extol the virtues of carefully gathering evidence without pretending that this will ever be the only driver of our decisions. And let's keep the umpires behind home plate, even if they are unduly affected by the roar of the crowd and the rhythms of the game.