There was an interesting tidbit in this morning's Washington Post discussing some reasons why Hillary Clinton performed better than the polls expected in the New Hampshire primary. Because the link may go away I've included the relevant quote below:
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.
This, of course, is what survey methodologists refer to as primacy, the tendency in self-administered surveys for respondents to choose responses disproportionately from the top of the a list of possible answers. In case you don't follow these things closely, Clinton's margin of victory was three percent.