Thursday, October 1, 2009

Why Bill James is Like Karl Popper

I’ve been a Bill James fan since some time in the early eighties. Actually I’m a fan of two guys named Bill James, but this is not about the British crime writer. I’ll write about him some other time. This is about the American baseball analyst, or as he prefers to call himself, “sabermetrician”. (The term is derived from an organization devoted to statistical analysis of baseball, the SABR or Society for American Baseball Research.) I’ve been an admirer of James ever since I first ran across his Baseball Abstract twenty-five years or so ago.

If you’re not especially interested in baseball, you might think Bill James is beneath your notice, but then my wife is not especially interested in baseball, and she thinks what James does is very interesting. That’s because she works in data analysis; she’s interested in what collected numerical data can tell us about the world. And anyone who has an interest in that topic can admire James’s work.

As anyone even slightly familiar with baseball knows, numbers have always been a big part of baseball: what’s he hitting, what’s his won-lost record, how many runs has he driven in? What Bill James did, starting back in the seventies, was to think seriously about what baseball numbers really mean with regard to winning and losing ball games. He brought a trained statistician’s mind to the endeavor, along with a predilection to think outside the box, to look at what was actually happening instead of what the conventional wisdom said must be happening.

This coincided with the computerization of statistical data, which greatly facilitated the compilation and analysis of the numbers. SABR promoted the careful gathering of data by armies of amateur statisticians, and it all went into the computer, providing a vastly expanded pool of baseball data.

From looking at the data Bill James decided that a lot of what we were told about baseball was wrong. In particular, our evaluations of players and teams were faulty because we were looking at the wrong things. Batting average was not really the best measure of what a hitter was contributing to the offense; a pitcher’s won-lost record was practically useless in evaluating his actual effectiveness, a team’s home ball park distorted its overall statistics, misleading observers as to its true strengths and weaknesses.

James asked the question: what individual actions on a baseball field actually contribute to a team’s winning or losing games? His answers led him to buck conventional wisdom, claiming for example that bunting and stealing bases were high-risk strategies that often hurt the team because they squandered outs, which he called a team’s most precious commodity. He claimed that walks were an underrated offensive weapon and that on-base percentage and slugging percentage were better indicators of offensive performance than batting average.

James’s insights were not accepted by everyone. Michael Lewis’s 2003 book Moneyball tells how Oakland A’s general manager Billy Beane struggled against conventional wisdom and baseball old-timers in applying James’s insights to his running of the team. But Beane made believers of a lot of people by using those insights to build a small-market, low-payroll team into a perennial contender by acquiring players who were undervalued by other teams but had the skills James insisted were crucial to baseball success.

It took a couple of decades, but Bill James changed the way people understand baseball. Today newspaper sports sections publish players’ OPS (on-base percentage plus slugging percentage) alongside their batting averages, and other James-originated concepts like range factor are routinely used in evaluating players. And James himself has now been hired as a consultant by the Boston Red Sox (who have won two World Series since adopting a Jamesian approach to player evalution), a supreme concession of respect.

So what does Bill James have to do with Karl Popper, or anything serious, for that matter? Listen to James in his essay “Intro to Sabermetrics” in The Bill James Gold Mine 2009: “[The entire difference between sabermetrics and traditional sportswriting] is merely the habit of beginning with a question, rather than beginning with an answer... The person who begins with the question itself naturally focuses not on what he does know, but on what he does not know.”

Now listen to Karl Popper: “...we do not start from observations but always from problems—either from practical problems or from a theory which has run into difficulties.”

James goes on: “Forced to confront his ignorance, [the researcher] is forced to find ways to figure out the information that he is missing... Through this process, he winds up contributing things that were not known before... We are never certain... We are just doing the best we can. Our methods are always flawed, and our answers are usually tentative and muddled... But the difference between knowledge and BS is that knowledge moves forward, whereas BS moves in circles... We wind up with methods that get better over time.”

Sound familiar? Here’s how Popper put it: “Scientific theories, if they are not falsified, for ever remain hypotheses or conjectures... The growth of knowledge proceeds from old problems to new problems, by means of conjectures and refutations.”

I don’t know if Bill James has ever read Karl Popper, but he’s a textbook example of the Popperian thinker at work, and his success in increasing our understanding of baseball is testimony to the power of Popper’s supremely rational approach to the accumulation of knowledge. He's only a baseball writer, but Bill James has a lot to teach any number of supposedly serious social scientists.

So give Bill James the Karl Popper Award for the Advancement of Knowledge, and take one last Bill James quote to heart: “... there will never be a shortage of ignorance... The things that we do not know are inexhaustible.”

Which echoes, of course, my favorite Karl Popper quote: “Our knowledge can only be finite, while our ignorance must necessarily be infinite.”

Sam Reaves
www.samreaves.com

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