The Effect of Candidate List Position on Vote Share: Improving Internal Validity and Expanding Scope Conditions

Objective When a candidate occupies a favorable position on a ballot, such as the top, they tend to secure a larger share of votes. Nonetheless, identifying position effects is challenging unless these positions are determined exogenously. I intend to improve the internal validity and expand the scope conditions of position effects analyses. Method The Japanese House of Councilors election offers an ideal natural experiment for internal validity because candidate positions are randomized across municipalities. Moreover, this case expands the scope conditions of position effects because (1) candidate names are displayed not on a ballot but on a list at the voting booth; (2) voters read the list from right to left and from top to bottom, thus making the top‐right corner, rather than the top‐left corner, the best position; and (3) the electoral system is a single nontransferable vote system, which has not yet been studied. Results When a candidate is located at the top‐right corner, the vote share is 0.560 percentage points greater than when they are located in another position. I cannot confirm other position effects. Conclusion The results suggest the primacy effect, namely, that the top position increases a candidate's vote share in Japan.