New Thinking in Political Economy series
Edited by José Casas Pardo and Pedro Schwartz
Chapter 14: The Unequal Treatment of Voters Under a Single Transferable Vote: Implications for Electoral Welfare with an Application to the 2003 Northern Ireland Assembly Elections
Vani K. Borooah* 1 INTRODUCTION The single transferable vote (STV) is a method of voting that allows voters to rank candidates (as opposed to parties) in order of preference. Under STV, each voter is allowed to write a number against the name of each candidate listed on the ballot paper, where this number expresses the voter’s preference for the candidate: the most preferred candidate has a ‘1’ against his/her name, the next most preferred a ‘2’, and so on. The ﬁrst stage of the count is to ascertain the total number of ﬁrst-preference votes for each candidate. Any candidate who has more ﬁrst-preference votes than the ‘quota’1 is immediately elected. If no candidate achieves the quota, the candidates with the lowest number of votes is eliminated and the second preferences on his/her ballot papers are assigned to the remaining candidates. If a candidate is elected at a particular count, the surplus votes (that is, votes in excess of the quota) are redistributed, according to the subsequent (or ‘next available’) preferences on the ballot papers, to the remaining candidates.2 National parliamentary elections in Ireland (Sinnott, 1993 provides a good analysis) – and elections to the Assembly and to local district councils in Northern Ireland – are underpinned by STV. It is also used in Malta and for elections to the Tasmanian – and the Australian Capital Territory – Legislative Assembly. The rationale for the STV method is twofold. First, each ballot paper is capable of expressing the preference ordering of voters over all the candidates...