The Signal and the Noise
The Signal and the Noise:
Why So Many Predictions Fail-but Some Don't
by Nate Silver
Penguin Press HC, The
$27.95 List Price
Political forecaster Nate Silver, who has made the frontiers of digital speculation his comfort zone, wants you to learn one thing above all else from The Signal and the Noise: Just because a prediction is wrong, that doesn’t mean it’s a bad prediction. And just because it’s right, that doesn’t mean the person who made it is smart.
Silver doesn’t offer one comprehensive theory for what makes a good prediction in his interdisciplinary tour of forecasting. But he does give us a well-worn literary analogy. Drawing on a pet image used by psychologist Philip Tetlock (who in turn adapted it from Isaiah Berlin, who cribbed it from Leo Tolstoy and Greek poetry), Silver explains that there are two main types of prognosticators: the hedgehog and the fox.
Hedgehogs, Silver says, are those who believe “in governing principles about the world that behave as though they were physical laws.” Foxes, by contrast, “are scrappy creatures who believe in a plethora of little ideas and in taking a multitude of approaches toward a problem.”
The author casts himself as a fox, and he thinks you should be one, too. As Silver explains, predictions typically fail when people—hedgehog people—ignore new information that conflicts with their worldview. And to remind us of how far afield the hedgehogs can wander, he cues up plenty of humiliating tape. There’s the economist who predicted a nine-percentage-point victory for Al Gore in the 2000 presidential ballot, based on an outmoded Vietnam-era model adapted from the computation of troop casualties. And there is the whole battery of Kremlinologists who
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