If the 2008 presidential election is any guide, the odds your vote will make a difference in the state of California are slim. Very slim. One in a billion, according to a study by Berkeley law and economics professor Aaron Edlin and his colleagues.
The researchers based their estimate on multiplying the probability that your state will be decisive in an electoral election times the probability that the election will be tied in that state. As a state grows more populous, it becomes more important in the electoral vote but less likely to have a tied election. But the more people who vote, the smaller the chances that your vote will make a difference. The national average, according to the study, is around 1 in 60 million.
Given those odds, Edlin says, most economists agree that the act of voting is irrational. Frustrated by that consensus, Edlin began to investigate the costs and benefits of voting to see if he could come up with a rational reason for why people vote. “I realized that as elections grow, of course the chances that you make a difference go down. But it’s also the case that what’s at stake goes up, because more and more people will be affected by the election.”
If a person votes for the public good, then it’s perfectly rational for them to vote, no matter how big the election, says Edlin. In a large election, you have the potential to make a big impact for a lot of people. For instance, the U.S. presidential election has a global effect. By electing a specific candidate, a voter can help bring about policies that provide social services, foreign policies, tax breaks, and other governmental benefits.
The rational model doesn’t hold for people who aren’t interested in the public good. “If you only care about yourself, you might as well stay home,” Edlin says. The rational model suggests that in large elections, the chance that your vote will count and the potential benefits you personally stand to gain are so small that it’s hardly worth the 15 minutes it may take to vote. The same holds true for landslide elections, where the outcome is clear, says Edlin.
All of this brings us back to California, a likely win for the Democratic presidential nominee and a state in which your vote only has about a one in a billion chance of being decisive. But, Edlin says, voters shouldn’t be discouraged because of the odds their vote will make a difference. Even if it’s small, the stakes may be large enough to make voting worthwhile. “You’d be awfully unhappy,” he says, “if your mother said that your vote would have made a difference and you hadn’t voted.”