Question wording and the house vote choice : some experimental evidence

Since 1978, the vote reported for House incumbents in the American National Election Studies (NES) has been significantly higher than the actual incumbents' vote in the districts surveyed; in NES surveys before 1978, the reported vote was much closer to the actual vote. The prime suspect for the source of this bias is the new question format introduced in 1978 and used in all subsequent studies. We document the problem and review the results of several question-wording experiments that confirm the superior accuracy of a format that does not mention the candidates' names over the ballot format currently in use. We also find evidence that a modified version of the ballot format may reduce the pro-incumbent bias, so that improvement may be possible without a major interruption of the post-1978 NES times series.