Tuesday, March 29, 2011

Why Experts Get the Future Wrong


NYTimes

What does the future hold? To answer that question, human beings have looked to stars and to dreams; to cards, dice and the Delphic oracle; to animal entrails, Alan Green­span, mathematical models, the palms of our hands. As the number and variety of these soothsaying techniques suggest, we have a deep, probably intrinsic desire to know the future. Unfortunately for us, the future is deeply, intrinsically unknowable.

This is the problem Dan Gardner tackles in “Future Babble: Why Expert Predictions Are Next to Worthless, and You Can Do Better.” Gardner, a Canadian journalist and author of “The Science of Fear,” takes as his starting point the work of Philip Tetlock, a professor at the University of Pennsylvania. Beginning in the 1980s, Tetlock examined 27,451 forecasts by 284 academics, pundits and other prognosticators. The study was complex, but the conclusion can be summarized simply: the experts bombed. Not only were they worse than statistical models, they could barely eke out a tie with the proverbial dart-throwing chimps.

The most generous conclusion Tetlock could draw was that some experts were less awful than others. Isaiah Berlin once quoted the Greek poet Archilochus to distinguish between two types of thinkers: “The fox knows many things, but the hedgehog knows one big thing.” Berlin admired both ways of thinking, but Tetlock borrowed the metaphor to account for why some experts fared better. The least accurate forecasters, he found, were hedgehogs: “thinkers who ‘know one big thing,’ aggressively extend the explanatory reach of that one big thing into new domains” and “display bristly impatience with those who ‘do not get it,’ ” he wrote. Better experts “look like foxes: thinkers who know many small things,” “are skeptical of grand schemes” and are “diffident about their own forecasting prowess.” [...]

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