THE SINGLE TRANSFERABLE VOTE

The single transferable vote (STV) is a family of vote-counting procedures that use voters' rankings of candidates as input and achieve proportional representation. This paper compares STV with other types of voting procedures and discusses the history of STV, issues concerning the rules of STV, limitations of various versions of STV, and a new version of STV based on paired comparisons of sets of candidates. Each refinement of STV overcomes a limitation of previous versions but at some cost in either the difficulty of understanding the procedure, the cost of computing the outcome, or both.