Elections under the single transferable vote (STV) electoral system comprise a ‘generally
neglected’ area of study, part of a class of ordinal systems ‘relatively less well
understood’ than their main alternatives, majoritarian or pure proportional systems
(Bowler and Grofman 2000, 6). Many students of electoral systems find STV of great
theoretical and practical interest, as it produces or at least provides incentives for a
considerably richer range of behaviours than other systems (Bowler 1996). Yet there are
relatively few examples of STV systems, making it difficult to draw inferences about
their effects in comparative studies of electoral systems.
The best-known examples of STV are found in a few cases at the national and
sub-national levels, in Ireland, Malta, the Australian Senate, and Tasmania. But there are
also historical and some contemporary examples in local government in the United States
(Amey 1993), Canada, (Johnston and Koene 2000) and New Zealand (Watson 2003).
Across most of these cases, it is rare to encounter sufficiently reliable data with which it
is possible to apply systematic analysis of STV outcomes in comparison to those under an
alternative system such as single member or multi-member plurality (hereafter nominal-
plurality, or NP) systems, under more or less the same conditions.
1
Puzzles and Expectations
By way of its ordinal ballot structure STV allows voters to express their preferences for
candidates with greater freedom and sophistication. Depending on district magnitude,
STV will produce results that are more proportional to voter preferences than NP
systems. STV therefore minimises wasted votes for unelected candidates, making
elections more competitive. This should have the effect of enhancing turnout (Franklin
Convention