“HOW TRUMP WON” blares the headline on this week’s Time magazine cover in 80-point Duplicate Ionic. “Now he just needs the votes,” whispers the small subheadline underneath.

Oh, just that little detail? Trump actually needs people to vote for him? I’ve been encountering a lot of this lately: Coverage implying that Trump’s lead atop the Republican polls (which he’s held since mid-July) is a watershed event, perhaps even tantamount to his having won an election.

These headlines, needless to say, are presumptuous. National polls, even with barely more than three weeks to go until the Iowa caucuses, aren’t highly predictive of the eventual outcome of nomination races. I know, I know: You’ve heard this spiel from us (and others) before. In fact, if you read this website regularly, you’ve been hearing it for nearly as long as Trump has been atop the polls.

To our credit — and perhaps to our ultimate detriment — we’ve at least been fairly consistent about this. If you’re not convinced about the empirical validity of national primary polls in the first place, having more of them doesn’t necessarily persuade you, any more than someone with a shellfish allergy is poised to take advantage of Red Lobster’s Endless Shrimp promotion.

But if Trump’s polls don’t quite mean what the headlines imply, what do they mean exactly? And even if you take them with a dose of skepticism, could he win the nomination anyway? (Spoiler alert: Yes, although I continue to think Trump’s chances are lower than where betting markets put them.)

Before we all decamp for Des Moines next week, let’s take one more theoretical look at the Republican race. In fact, we’ll take three of them. As far as I can tell, there are three main theories about the rise of Trump; respectively, they pin the credit (or blame) for Trump on Republican voters, Republican elites and the news media. Each theory interprets his polls differently and comes to different conclusions about how much staying power he might have in the new year.

Read the article “Three Theories of Donald Trump’s Rise” on fivethirtyeight.com.