Inexact, but science

Inexact, but science

Last Updated: Wed, Nov 07, 2012 04:10 hrs

Forget the spin: Barack Obama retains a narrow edge in Tuesday’s US election. Economy-based models and US national polls show the president and Republican challenger Mitt Romney neck-and-neck. But under the state-by-state system that ultimately determines who will occupy the White House, Obama leads.

The popular vote contest provides good headlines. A model based on economic inputs developed by Ray Fair at Yale University put Obama’s share of the vote at 49 per cent late last month. Given the margin of error, that really means it’s a toss-up at the national level. This close to the election, polls are probably a better gauge. In the average calculated by RealClearPolitics, Obama was a narrow 0.4 percentage point ahead as of Monday morning, reversing the slim advantage Romney opened up in October after Obama’s heftier lead the month before.

But the national vote doesn’t decide the presidency. Instead, that falls to an electoral college of 538 representatives, allocated to states according to the size of their delegations in Congress, which very roughly approximate their populations. Most states have a winner-takes-all system that awards all electors to the candidate who gains a majority of votes. That makes winning individual swing states crucial.

The states solidly for Obama or Romney give the incumbent a 201-191 vote advantage in the electoral college, RealClearPolitics reckons. But 270 votes are needed to win, and plenty of states are close in the polls. Adding current polling data for those places into the mix gives it to Obama 303 to 235. Nate Silver, a statistician-pollster famed for almost spot-on predictions in the 2008 election, has the tally at 307 for Obama and 231 for Romney.

Despite uncommon mathematical rigor, Silver’s work has earned him the ire of Republican pundits. But there’s a misunderstanding built into some of the criticism, too. Silver pegs the odds of Obama’s victory at 86 per cent as of early Monday morning. That sounds huge, and contrary to the closeness of national polls. But it’s precisely because presidential elections are usually tight that a small edge in a few key states can produce a heavy favourite.

The market in election odds is a bit less bullish on Obama. Punters using InTrade pegged his odds of re-election at around 67 per cent as of Monday morning. That doesn’t mean he’ll win for sure. Romney’s spin-masters are laying out combinations of state wins favouring the underdog. And, a worst-case outcome for other financial markets, a disputed election hanging on one or two close state votes as in 2000, can’t be completely ruled out. But taking the electoral system into account, Obama’s odds look at least twice as good as Romney’s.

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