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

by Nate Silver

“It’s critical to have a diversity of models,” I was told by Kerry Emanuel, an MIT meteorologist who is one of the world’s foremost theorists about hurricanes. “You do not want to put all your eggs in one basket.” One of the reasons this is so critical, Emanuel told me, is that in addition to the different assumptions these models employ, they also contain different bugs. “That’s something nobody likes to talk about,” he said. “Different models have different coding errors. You cannot assume that a model with millions and millions of lines of code, literally millions of instructions, that there isn’t a mistake in there.” If you’re used to thinking about the global warming debate as series of arguments between “skeptics” and “believers,” you might presume that this argument emanates from a scientist on the skeptical side of the aisle. In fact, although Emanuel has described himself as conservative and Republican40—which is brave enough at MIT—he would probably not think of himself as a global warming skeptic. Instead, he is a member in good standing of the scientific establishment, having been elected to the National Academy of Sciences.