How electoral reform alters legislative speech: Evidence from the parliament of Victoria, Australia 1992–2017

Abstract

Does changing single-member district (SMD) systems to proportional representation (PR) systems affect politicians' behavior? Previous studies, which have utilized cross-sectional or temporal variation in electoral systems, fail to estimate their effects. In contrast, we employ a difference-in-differences design and text analysis to estimate the causal effect of an electoral reform on politicians' issue attention. In particular, we estimate the causal effect of the electoral reform in the Parliament of Victoria in Australia, which changed the electoral systems of the Legislative Council from SMD to PR while holding the system of the Legislative Assembly constant. We analyzed a newly collected dataset of legislators' inaugural speeches from 1992 to 2017 using a topic model. The results show the electoral reform increased politicians’ attention to new economic issues but did not decrease attention to local interests such as promoting primary industries.