「混合選制」下選民之一致與分裂投票：1996年日本眾議員選舉自民黨選票之分析

Abstract

The 1990s witnessed an explosion in electoral reforms, especially in adopting the ”mixed electoral systems” which combine the features of both single-member districts (SMD) and proportional representation (PR). In January 1994, the Japanese Diet passed the law that replaced the single nontransferable vote (SNTV), in use since 1947, with a mixed-member majoritarian (MMM) system. Voters cast two votes in this new electoral system: a candidate vote in an SMD, and a party-list vote in the list tier portion of the ballot. The 1996 House election was the first test of the MMM system in Japan. The purpose of this article is to assess the effects of this electoral system change based on the 1996 post-election survey of the Japanese Election Study (JES). We focus particularly on the straight-and split-ticket voting patterns for the Liberal Democratic Party (LDP) and their determinants. Our study indicates that straight-ticket rate was pretty high among the LDP supporters. That is, 80.16% of those who voted for an LDP candidate in an SMD also voted for the LDP on a party-list vote. A further analysis reveals that the LDP identifiers and the more conservative were much more likely to cast straight votes for the LDP, but on the other hand voters with college-level or higher education were less likely to do so. We also find that between two types of ticket-splitters, the percentage of voters who voted for an LDP candidate in an SMD and yet for the non-LDP on a party-list ballot was higher than those who voted the other around. This is probably due to the fact that some non-LDP party identifiers voted strategically in SMDs for the largest party's (i.e., the LDP) candidates, on the one hand, and yet voted sincerely for the non-LDP on the party-list ballot.