日本自民黨之選票穩定度研究：1993、1996及2000年眾議院選舉之定群追蹤分析

Abstract

Japanese party politics witnessed a dramatic change in 1993. The then ruling Liberal Democratic Party (LDP), which had dominated the Japanese politics since 1955, lost its majority seats in the 1993 House of Representatives election. Three years later, however, the LDP staged a comeback and played the major role in forming the new coalition government. It managed to maintain this control in the 2000 House election. We are curious about how Japanese voters responded to the turmoil of Japanese party system during this period. Taking advantage of a panel data of the Japanese Election Study (JES), we explore the dynamics of electoral stability and change of the LDP supporters during the 1993, 1996 and 2000 House elections. Among several Markov chain models analyzed in this paper, we find that the Black and White model, a special case of the Mover-Stayer model, fits the JES panel data best. Specifically, this model splits subjects into two latent subgroups with maximum intragroup homogeneity and intergroup heterogeneity, each of which has its own estimated transition probabilities. The first subgroup (“stayers”), which consists of about 48.28% of the panel, always maintains its LDP or non-LDP party preference without any change. The second subgroup, which consists of about 51.72% of the panel, however, moves randomly. In 1993, 37% of “stayers” supported the LDP while 40.46% of “random movers” supported the LDP. In 1996 election, half of this 40.46% of “random movers” shifted away from the LDP while the other 59.54% non-LDP supporters shifted to the LDP. As a result, the LDP enjoyed a net gain of 4.93% in total votes in 1996. Since the Black and White model has reached its steady state after the 1996 transition, it indicates little net change in year 2000’s election.