Proportional Representation

Abstract

Proportional representation (PR) refers to electoral systems designed to approximate the ideal of proportionality in converting citizens' votes into legislative seats. All PR systems require multimember constituencies. The degree to which a PR scheme approaches proportionality increases with the number of representatives elected per constituency. In the most common form, list PR, electors vote for lists of candidates designated by parties. Any of several formulas allocate seats to parties, and parties select winning candidates from their lists according to predetermined rankings. In a less common version, the single-transferable vote (STV), voters rank individual candidates, criss-crossing party lines if they wish. In a third type, mixed-member proportional (MMP), about half the representatives are elected from single-member districts (SMDs) and half from party lists, but seats won in SMDs are subtracted from list allocations so they do not diminish overall proportionality. Compared with electoral systems based on plurality or majority rule, PR is conducive to multiparty legislatures and coalition governments. After development during the nineteenth century, PR methods were first adopted for national elections by Belgium in 1899. Almost three-fifths of well-established democracies use PR to elect their principal legislature chambers.