By this point in the campaign season, the presidential polls may have your head spinning. Romney’s up 7 points in one, Obama’s up 3 in another … and on any given day, a dozen other polls are swirling, each offering a different take.
But there is a market out there that distills all those data down to one simple predictive number — and gives you a chance to bet on it. [cont.]
John Ydstie, NPR