There’s much to be said about Brexit. Start with Tim Lee’s rundown of what comes next, and Matt Yglesias’s look at the winners and losers.
But here’s a simple lesson from the GOP primaries and from Brexit: Polling is proving a much better guide to political outcomes right now than recent history or established norms.
We saw this during the Republican primaries. Donald Trump led poll after poll, but seasoned political observers simply refused to believe he would win. I was one of those skeptics, and I had no shortage of company. Even analysts who stick close to the numbers refused to believe the data. "Dear media, stop freaking out about Donald Trump’s polls," demanded Nate Silver. For months, American political punditry was little more than an escalating series of rationalizations for why the guy dominating the polls would obviously, inevitably lose the primary.
And then, of course, he won.
Brexit followed much the same path. Even as the polls tightened, elite sentiment remained confident. On the eve of the vote, polls showed "Leave" even with "Remain," but betting markets overwhelmingly assumed Britain would stay in. "I also walked by the European Commission in Brussels," reported economist Tyler Cowen, "and saw not the slightest sign of panic or for that matter interest."
And then, of course, Leave won.
On some level, we’re all good Bayesians: We’re skeptical of data that baldly contradicts how we know the world to work. But in politics right now, the world isn’t working the way we think it does. Polling is proving a much more reliable guide to political outcomes than the "does-this-seem-insane?" test most people use to guide their predictions.
The lesson here is not that the least likely, most disruptive outcomes are suddenly a safe bet. Brexit’s win doesn’t predict Trump’s victory, contrary to some of the chatter I’ve seen on Twitter. Rather, when evaluating the likeliest outcomes, look to trustworthy polls rather than your gut. Hillary Clinton’s 7-point lead over Donald Trump still makes her the favorite, but if those numbers flip, take it seriously. Pundits who stick to their priors even when the data tells them to abandon ship are not faring well this year.
