WASHINGTON

Two economists, Brian Knight and Nathan Schiff, set out a few years ago to determine how much Iowa, New Hampshire and other early-voting states affected presidential nominations.

Mr. Knight and Mr. Schiff analyzed daily polls in other states before and after an early state had held a contest. The polls tended to change immediately after the contest, and the changes tended to last, which suggested that the early states were even more important than many people realized. The economists estimated that an Iowa or New Hampshire voter had the same impact as five Super Tuesday voters put together.

This system, the two men drily noted in a Journal of Political Economy paper, “represents a deviation from the democratic ideal of ‘one person, one vote.’ ”

A presidential campaign is once again upon us, and Iowa and New Hampshire are again at the center of it all. On Thursday, Mitt Romney will announce his candidacy in Stratham, N.H. Last week, Tim Pawlenty opened his campaign in Des Moines. The two states have dominated the nominating process for so long that it’s easy to think of their role as natural.