The Signal and the Noise: Why So Many Predictions Fail-but Some Don't

by Nate Silver

It seems like cheating to change your mind—the equivalent of sticking your finger out and seeing which way the wind is blowing.29 The critiques usually rely, implicitly or explicitly, on the notion that politics is analogous to something like physics or biology, abiding by fundamental laws that are intrinsically knowable and predicable. (One of my most frequent critics is a professor of neuroscience at Princeton.30) Under those circumstances, new information doesn’t matter very much; elections should follow a predictable orbit, like a comet hurtling toward Earth. Instead of physics or biology, however, electoral forecasting resembles something like poker: we can observe our opponent’s behavior and pick up a few clues, but we can’t see his cards. Making the most of that limited information requires a willingness to update one’s forecast as newer and better information becomes available. It is the alternative—failing to change our forecast because we risk embarrassment by doing so—that reveals a lack of courage.