Methods 101: Why the NH Polls Were Wrong

Jon Krosnick, a professor of Communication at Stanford and perhaps the top expert in survey methodology, hypothesizes that the pre-primary polls in New Hampshire might have been wrong because they failed to take into account the NH ballot design and the miserly nature of voters. In public opinion research, the tendency for miserly voters to choose the candidate listed first or closer to the top of the list of candidates is called the primacy effect:

A further potential source of error stems from New Hampshire ballot rules. In previous contests, the state rotated candidate names from precinct to precinct, but this year the names were in alphabetical order, with Clinton near the top and Obama lower down. Stanford Professor Jon Krosnick, a survey specialist and expert witness in a lawsuit about ballot order in New Hampshire, has estimated a three percentage point or greater bounce for a big name candidate appearing high on the ballot. Therefore, if pre-election polls randomized candidate names, as most do, they would have underestimated Clinton’s support by at least three points.

Regardless, there were no immediate clear answers, and lots of data analysis ahead.