An ecological inference approach to the origins of proportional representation

Abstract

Facing a prospective majority of socialists during the early third of the 20th century, some secular conservative and liberal parties pooled their votes to raise the majority threshold for the left, while others raised it by enacting some form of proportional representation. We use vote transfers, estimated by a new method of ecological inference, to explain those far-reaching choices. We provide a new conceptualization and measurement of the segmentation of the electoral market to test a proposition within the Boix-Rokkan framework: proportional representation reform was chosen when vote transfers foretold coalition failure. To substantiate our claim, we investigate two most similar cases, Denmark during 1910–1918 and New Zealand during 1928–1931, that diverged in the explanatory variable and in the response.