Larry Sabato looked at research on the effect of ballot position on election results. Most of the findings were predictable. Being first helped more the less voters were likely to know the candidates or have some other reason to make a choice. Position mattered less in high profile races such as president, governor, or senator as voters were more likely to know something about the candidates. Position also mattered less in partisan elections as many vote based upon party. Nonpartisan elections and primaries within a party did not allow people to vote along party lines making position matter more. Having a well-known incumbent on the ballot reduced the effect of position.
There was one item which might be a surprise. While being first gave the largest advantage, the next greatest advantage was being last. Voters who did not know who who to vote for tended to pay the most attention to the first and last names on the list.
