Watch Virginia and Indiana says political analyst

What to watch for this evening? It could come down to just two states.

The polling site FiveThirtyEight.com has the lowdown on what to watch out for at 7 p.m. (Eastern Time) tonight.

Virginia and Indiana

Is it a safe bet to call it that early? Nate Silver, the baseball statistician turned all-star political analyst, says yes. The key is Virginia and Indiana.

Says Silver, "If those states go roughly as expected (meaning, say, an Obama win in Virginia and a close race in Indiana), we can conclude with almost literal 100 percent certainty that Obama will win the election."

More wonks

He cites another wonk (Andrew Gelman of Columbia University) who took Silver's work and ran 10,000 simulations and came up with a bunch of stuff we don't understand -- except the bottom line: Obama wins if the above criteria are correct.

Now, what if the vote margin in Virginia, Indiana, Georgia, South Carolina, and Kentucky were to equal the expected -5.7%?

We pipe this assumption through our model by calculating, for each of our 10,000 simulations, the average vote margin in these five states, and then restricting our analysis to the subset of simulations for which this vote margin is within 1 percentage point of its expected value (that is, between -6.7% and -4.7%).

Out of our 10,000 simulations, 2800 fall in this range; that is, we predict there is a 28% chance that McCain’s average vote margin in these five states will be between 4.7% and 6.7%. What is of more interest is what happens if this occurs.

Considering this subset of simulations, Obama’s expected national popular vote margin is +4.7%, his expected electoral vote total is 343, and the conditional probability of an Obama victory is 100%: he wins the electoral college in all 2800 simulations in this condition.

Make sense? You're smarter than we are.

But go to Silver's web site here for some background.