Candidates who win the New Hampshire primary historically have a 60 percent chance of winning the nomination, “which is very high, given that there is still a large number of candidates and primaries to go in the race,” says Tilman Klumpp, assistant professor of economics.

Presidential candidates tend to spend up to 75 percent of their campaign budgets in the lead-up to the primaries in Iowa and New Hampshire, as they seek to gain this early advantage of momentum, notes Klumpp, who uses economic tools to study political science questions.

Several states have sought to move their 2008 primaries to earlier dates, to try to dilute the New Hampshire effect. So why not hold all the primaries simultaneously, to eliminate the chance of the momentum?

Cost is likely one key reason, Klumpp says. Together with a colleague, Klumpp developed a mathematical model to study the impact of holding all the primaries on one day. “The primary campaign expenditures, according to our model, would rise significantly,” he says.