At 9:46 p.m., blogging on his site FiveThirtyEight.com, Nate Silver called the presidential election for Barack Obama. The television networks followed suit about an hour and 15 minutes later after most polls in Western states closed.

Of course, Mr. Silver had a head start: he had forecast that Senator Obama would beat Senator John McCain back in March.

In an election season of unlikely outcomes, Mr. Silver, 30, is perhaps the most unlikely media star to emerge. A baseball statistician who began analyzing political polls only last year, he introduced his site, FiveThirtyEight.com, in March, where he used his own formula to predict federal and state results and run Election Day possibilities based on a host of factors.

Other sites combine polls, notably RealClearPolitics and Pollster, but FiveThirtyEight, which drew almost five million page views on Election Day, has become one of the breakout online stars of the year. Mr. Silver recognized that people wanted to play politics like they played fantasy baseball, and pick apart poll numbers for themselves instead of waiting for an evening news anchor to interpret polls for them.