By-elections have received relatively scarce scholarly attention, and common features identified by existing works largely derive from studies of Western countries with relatively stable patterns of party competition. The following pages contribute to the literature by examining by-elections in the Japanese House of Representatives since electoral reform in 1994. Changing patterns of party competition adds interest to observing by-elections taking place in the context of an evolving two-party system. The paper discusses how results from Japanese by-elections conform to, or deviate from, expectations based on findings from previous studies, in terms of the frequency and direction of seat changes, the turnout rates, the presence of minor party and independent candidates and the timing of by-elections during the legislative period. It then tests the impact of these factors, along with government approval ratings and macroeconomic indicators, on governing party performance in by-elections. The number of candidates, cabinet support and prefecture-level unemployment rates are found to exert a significant influence. Separate analysis is also carried out for by-elections characterized by head-to-head contests between the two major parties.
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