Policy preferences and party switching: Evidence from the 2012 Japanese election

Abstract

In 2012, despite controlling more than 60% of all seats in Japan’s lower house, the Democratic Party of Japan had roughly 100 legislators switch parties. The break-up proved so disastrous that the DPJ collapsed and Japan’s steadily developing two-party system utterly collapsed, marking one of the most momentous events in recent Japanese political history. However, there is little systematic understanding of what produced this outcome. I leverage a dataset of candidate policy preferences in order to pinpoint what led politicians to take the dramatic step of leaving the ruling party. Through factor analysis and logistic regression, I find that DPJ incumbents with policy preferences significantly different from their party were especially likely to switch and that those preferences predict the party they ultimately chose.