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Who will win the White House in 2012? What the polling tells us | Harry J Enten

Much is made of ‘swing states’, but it’s the national vote that decides US elections – and that’s driven by economic sentiment

Presidential candidates win by accumulating a majority of votes (270) in the electoral college, not by winning the most votes nationwide. That’s why you’ll hear analysts talking about the “swing states”, but the truth is that presidential campaigns are mostly national. 

Consider the last two really tight presidential elections, in 2000 and 2004. You may remember that Al Gore won the national vote in 2000 by about 0.5 of a percentage point; yet he lost the presidency. This would seem to argue against my point, except that he only lost Florida by 0.01 of a point. So that is still a difference of only 0.5 of a percentage point between the tipping-point state and the national vote. That may be a tremendous practical difference, but numerically, it’s nothing.

How about 2004? All attention was on “Ohio, Ohio, Ohio”, and it was the closest state. George W Bush won it by 2.1 percentage points, and that was pretty much identical to his 2.5-point victory nationwide. Again, this might have been very important in the tightest of races, but it really isn’t something that should have pundits in a tizzy.

In 2008, it turned out that you could have applied a “uniform swing” (that is, add 4.5% – Obama’s improvement over John Kerry’s national percentage – to John Kerry’s vote percentage in each state) and come within 3% of Obama’s vote percentage in most states. This graph by the venerable Andrew Gelman illustrates this point. (Note the only true exception to the rule was Hawaii, Obama’s birth state.)

My point here is not that campaigns in the swing states cannot move voters (since evidence from 2008 suggests that it can, to a degree), but it’s the overarching economic factors driving the national race that are mostly responsible who wins in any given state.

If the race is within a percentage point or two in the final weeks of the campaign, then yes, you should pay attention to the state polling. Otherwise, nationally polling is not only more accurate, but it also catches trends faster.

The one thing you should absolutely not do right now is pay much, if any, attention to polls projecting the November vote. Pioneers Chris Wlezien and Bob Erikson have found that the relationship between polls now (some 280 days before the election) and the eventual vote is almost nil. In the chart below, the line tracks how much of the eventual vote is explained by the polls on any given day.

The polls do a better job in the March and April (that is, when we will probably know who the Republican nominee is), but they still aren’t that predictive. 

Presidential approval ratings will also matter more in March. By April, presidential approval accounts for about 60% of the November vote. Still, that leaves an awfully large chunk of the vote unexplained, and approval should not be used for anything more than a hint of how the election result might end up. 

Favorability ratings, approval’s close cousin, are not any better at this point. Gallup’s net favorable (favorable/unfavorable) ratings at this point in the last five campaigns sometimes hold through the election – and sometimes they do not.

There can be wide swings in net favorability because competitive primaries leave candidates temporarily bruised, and the voters have not fully recognized the state of the economy. We even have a case where a candidate, Bill Clinton, with a net unfavorable at this point in the campaign, went on to win the election. In fact, Bill Clinton’s net favorable would drop to -12 percentage points in April of 1992, before rebounding later that year. 

So, is there anything predictive we can know about the 2012 vote, at this point? 

History tells us that it’s the economy that will hold the key for Obama’s re-election prospects. Right now, the economy is probably not good enough for Obama to be re-elected. Across a number of economic data points, the past three years have been among the worst in the past 60 years. Even with a modest improvement in the economy, Obama would still be a slight underdog – though he would certainly have a more than fair chance of winning. 

For now, we must wait to see how much the economy improves and how the campaign takes shape. Right now, the state and national polls are chiefly fun to watch. Eventually, they will really mean something, too. But not yet.

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