Designing electoral institutions: STV systems and their consequences

Although championed by advocates of proportional representation, the single transferable vote form of PR has been used consistently in only a small number of countries - principally Australia, Ireland and Malta. This paper examines the origins and development of STV and its implications for the political systems that use it. The results show that STV varies so widely in its form and application, differing on no less than five major characteristics, that it is impossible to identify any single generic type. These differences are also reflected in the party strategies that are used to maximize the vote under STV. A regression analysis of the various types of STV shows that Malta is the most proportional system, followed by Ireland and Tasmania. Ireland has the largest party system among the countries that use STV, net of other factors.