Odds of single vote deciding election: 1 in 60M

[November 03, 2008]  WASHINGTON (AP) -- Voting for president and having your ballot be the deciding one cast -- statistically, that is like trying to hit the lottery. The odds for the average person are 60 million to 1 against it, a study shows.

In some states, the odds of being the vote that tips the election to your candidate are much better. In others they are astronomically worse.

The study by three prominent statisticians used millions of computer runs of polling data to examine the likelihood that a single vote will carry a state and that that particular state will tip the balance in the Electoral College. The statisticians were trying to answer the question: "What is the probability your vote will make a difference?"

The answer is very low. You are far more likely to be hit twice by lightning.

Trying to figure out what the odds would be if the polls are wrong and the race is tighter than expected, the statisticians made some more calculations after boosting John McCain's numbers across the board and figured the average person would then have a 1 in 12 million chance of their vote deciding the election.

Either way, "it's still a chance, it's like buying a Powerball ticket," said study lead author Andrew Gelman, a professor of statistics and political science at Columbia University.

For some people, though, the odds approach fathomable numbers. Residents of swing states have the best odds of swinging the election. That's based not on the size of the state but the likelihood that the race will be close and that their state will make the difference in the Electoral College.

In New Mexico, the odds are 1 in 6.1 million of a voter casting the ultimate deciding vote.

"If you're in New Mexico, you have a better chance of having your vote matter than winning the New York Lottery," said study co-author Aaron Edlin, a professor of economics and law at the University of California, Berkeley.

In Virginia, the odds are 1 in 7.9 million. New Hampshire residents have 1 in 8 million chance of being the key vote. In Colorado, the odds are 1 in 9.9 million. In those states, voters are more likely to decide the election than die by dog bite this year.

For everyone else after those four states, fat chance. The next lowest odds -- for Nevada -- are 1 in 28.2 million, worse than death-by-dog bite odds of 1 in 10.9 million in one year.

Thirty-four states have odds greater than 1 in 100 million; 20 states have odds worse than 1 in 1 billion. Alabama's odds are 1 in 12.2 billion. Oklahoma's odds are 1 in 20.5 billion. But the nation's capital has it the worst. The odds of a District of Columbia resident casting the vote that decides the election are 1 in 490 billion.

That's essentially zero, but Gelman said: "We never like to say zero in statistics."

The third author is prominent baseball statistician Nate Silver, who also runs the political polling Web site http://www.fivethirtyeight.com. (There are 538 electoral votes nationwide.) The polling used for their study is from Silver's Web site and aggregates numerous polls of varying standards.

Even though the odds are against their own votes making a difference, the authors plan to vote, mostly out of altruism and civic duty. And they urge everyone to do so, no matter what the odds of their vote being the deciding factor.

Gelman lives in New York, where the odds are 1.9 billion to 1 that his vote will make the difference. "I always vote," he said. "I do think that it's a privilege that we have."

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On the Net:

Election odds study: http://tinyurl.com/6y3toe

Electoral College: http://tinyurl.com/yryxbx

[Associated Press; BY SETH BORENSTEIN]

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