TOWARD A CONTEXT-RICH ANALYSIS OF ELECTORAL SYSTEMS - THE JAPANESE EXAMPLE

Theory: Political parties receive a greater or lesser percent of seats than their percent of the vote in an election for a variety of reason s. District magnitude, the type of the electoral system, and strategic errors are three inherent features of an electoral system that affect seat bonuses. Malapportionment and turnout differentials are features specific to a country that also affect seat bonuses. Hypotheses: If e ach of the above sources of seat bonuses is isolated out and measured, then we will find that neither the malapportionment of the Japanese e lectoral system nor the strategic efficiency of the Liberal Democratic Party in Japan (LDP) explains entirely the LDP seat bonus. Methods: A n analysis of seat-bonus components using a logistic regression model and recalculations of seat bonuses after adjusting for specific factor s. Results: The LDP receives most of its seat bonus from district magn itude and to a lesser degree from malapportionment. The LDP is hurt by the net effect of strategic errors and to a small degree from the inf luence of turnout differentials.