Proportional representation: Difference between revisions

'''Proportional Representation''' ('''PR''') describes various multi-winner [[electoralvoting system]]s which try to ensure that the proportional support gained by different groups is accurately reflected in the election result. Proportional representation is also used to describe this (intended) effect.

In practice this usually involves ensuring that [[political party|political parties]] in [[parliament]] or legislative assemblies receive a number of seats (approximately) proportional to the percentage of vote they received. This is known as [[party-list proportional representation]]. Another kind of electoral system that strives to achieve proportional representation but which does not rely on the existence of political parties is the [[single transferable vote]] (STV). Some electoral systems, such as the [[single non-transferable vote]] and [[cumulative voting]] are sometimes categorized as "semi-proportional".

Electoral systems that do not result in proportional representation are known as [[majoritarian system]]s. These include [[first-past-the-post]] (plurality), [[runoff voting]] (majority), the [[alternative vote]] and the [[bloc vote]]. HereIn these systems, parties can receive seat numbers that bear little or no relationship to the national percentages they received in parliament. This is called disproportionality, and can be measured with the [[Gallagher Index]] (or [[Least squares]]), which takes the [[square root]] of half the [[sum]] of the [[square (algebra)|square]]ssquares of the difference between percent of vote and percent of seats for each party.

Proportional representation is unfamiliar to most citizens of the [[United States]], but it is actually a much more common system of voting than first-past-the-post. In general, first-past-the-post is only used in former British colonies, but a form of proportional representation known as the [[mixed member system]] is now being used in the [[United Kingdom]] to elect the members of the [[Scottish Parliament]] and the [[Welsh National Assembly]]. Although once an unknown system, Proportional representation is now gaining popularity in [[Canada]] with three provinces: British Columbia, Ontario and Quebec, now committed to abolishing first past the post, at the federal level, a Parliamentary Committee is now exploring the issue and many Canadians are showing interest in adopting a form of Proportional Representation. Political analysts point out the fact that the current attitude and sequence of events is very similar to what happened in the [[New Zealand]] when, New Zealand opted for Mixed Member Proportional Representation and the analysts conclude Canada is heading down the same route. All of the members of the European Parliament, or [[MEP]]sMEPs, including those elected from constituencies in Britain, are elected by proportional representation. Proportional representation is also used in many European countries.