The transformation of Australian electoral analysis

Measuring party support in Australia by constructing a "two-party preferred" vote has had a profound effect, not only on the way political scientists, journalists, and politicians understand electoral "swing" and predict electoral outcomes, but also on their understanding of the party system, their thinking about electoral fairness, and their views about which party or parties can legitimately claim government. This article traces the origins - the maternity as well as the paternity - of the "two-party preferred". It documents its spread from federal to state elections, even as voting systems in some states have switched from exhaustive preferential to optional preferential. It discusses its wide-ranging impact, and its implications for notions of electoral fairness and the legitimacy of election outcomes. It evaluates various criticisms of the concept - technical, pragmatic, and conceptual. And it notes the implications for marginal seat campaigning of the commonly observed "uniform swing"- implications completely at odds with the idea that marginal seats matter.