Strategic voting in established and new democracies: Ticket splitting in mixed-member electoral systems

Using Cox’s ’SF-ratio’ (the ratio of the vote won by the ’second loser’ to that of the ’first loser’), we examine strategic voting in mixed-member electoral systems in ten countries and a total of 35 elections. The SF-ratio is a useful indicator of strategic defection from less competitive to more competitive electoral options that is comparable across very diverse country cases. Under conditions of a Duvergerian equilibrium, where there is substantial information indicating which candidate is likely to end up the top challenger to the frontrunner, the SF-ratio for a district will tend toward zero. In contrast, in cases where voters either are unwilling or unable to cast strategic ballots, SF-ratios will tend to be higher. Our findings show substantial evidence of strategic voting in established democracies, particularly in districts with closer races, but little evidence of strategic voting in new democracies with poorly institutionalized party systems. 2008 Elsevier Ltd. All rights reserved. There have been a number of studies of ticket splitting under two-ballot mixed-member electoral systems. In many ways, such systems offer an ideal arrangement for understanding ‘‘horizontal’’ ticket splitting (see Burden and Helmke’s introductory article). Under these mixedmember systems, voters cast two ballots simultaneously to elect representatives to a single branch of the legislature. They cast one ballot for a candidate in a single member district (SMD) and one for a party in a proportional representation (PR) contest. Because these two votes are cast under different electoral rules, mixed-member systems are also ideal laboratories for examining the sources of split-ticket voting. Scholars have regularly used the difference in aggregate vote totals – usually at the district level – to argue that much of split-ticket voting in mixed-member systems is founded on strategic voting rather than, for example, strategic balancing of different parties to achieve a certain