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engaged in direct confrontation for the common pool of leftist voters. The table, in fact, is
suggestive of JSP’s fundamental dilemma under SNTV in that, by nominating more
candidates, this party was expected to gain seats in its competition vis-Ã -vis the JCP, but
simultaneously expected to decrease its seat-share in its competition with its main rival, the
LDP (Kohno 1997b).
In sum, the compositional data analysis and the accompanying simulation results
based on the actual outcomes of elections held from 1958 to 1990 unambiguously
demonstrate that under the SNTV system, a majority seeking party, like the LDP (and the
JSP), was not always able to improve its electoral performance by adding another candidate
in electoral competition.
4. SNTV’s Strategic Effect on LDP’s Candidate Nomination
In this section, we turn to the substantive question, with which we began our investigation
originally, namely the relationship between the structural features of SNTV and the
establishment of the LDP’s one-party dominance in postwar Japan. Can we reject the
conventional wisdom that the steady reduction in the number of LDP candidates in the earlier
years reflected the socioeconomic erosion of the LDP’s electoral base? And, can we instead
substantiate that the LDP’s candidate nomination was strategic and politically determined
under SNTV’s mechanical pressure?
4.1. Method and Data
In order to analyze the determinants of LDP candidate nomination properly, we have created
a new data set, which includes relevant socioeconomic variables at the district level. In the
Convention