Proportional representation

Proportional representation (PR) is any election system which ensures a proportionally representative result of a democratic election, x% of votes should be represented by x% in the democratic institutions, parliament or congress.

Often only possible in various multi-winner electoral systems 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 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".


Majoritarian systems

Electoral systems that do not result in proportional representation are known as majoritarian systems. These include first-past-the-post (plurality), runoff voting (majority), the alternative vote and the bloc vote. Here, parties can receive seat numbers that bear no relationship to the national percentages they received in parliament. This is called disproportionality, and can be measured with the Gallagher Index.


The district or constituency magnitude of a system (i.e. the number of seats in a constituency) plays a vital role in determining how proportional an electoral system can be. When using proportional systems, the greater the number of seats in a district or constituency, the more proportional it can be. Any system with single-member districts is by necessity majoritarian at the district or constituency level. However, district or constituency borders may be gerrymandered to create "majority-minority" districts or constituencies where a group of voters in the minority system-wide form the majority in a particular district or constituency, thus allowing a simulation of proportionality system-wide.

However, multiple-member districts do not ensure that an electoral system will be proportional. The bloc vote can result in "super-majoritarian" results in which, in addition to the normal disproportionality of single-member majoritarian systems, geographical variations that could create majority-minority districts become subsumed into the larger districts.

There is also another cause of disproportionality within proportional system. This is when the party does not provide a list with enough people on it to fill all the seats won by a political party. For instance if a party wins 20 seats but only has 15 people on its list then it loses 5 seats. This is termed an underhang.


The PR system was devised in the early 20th Century, and was first used in European democracies such as the German Weimar Republic.

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 five provinces: British Columbia, Ontario, Quebec, Prince Edward Island and New Brunswick are currently debating whether to abolish the first past the post system, and at the federal level, a Parliamentary Committee is now exploring the issue. Political analysts point out the fact that the current attitude and sequence of events is very similar to what happened in 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 MEPs, including those elected from constituencies in Britain, are elected by proportional representation. Proportional representation is also used in many European countries.

Proportional representation does have some history in the United States. Many cities, including New York, once used it for their city councils as a way to break up the Democratic Party monopolies on elective office. In Cincinnati, Ohio, proportional representation was adopted in 1925 to get rid of a Republican party machine (the Republicans successfully overturned proportional representation in 1957).

Some electoral systems incorporate additional features to ensure absolutely accurate or more comprehensive representation, based on gender or minority status (like ethnicity). Note that features such as this are not strictly part of proportional representation; depending on what kind of PR is used, people tend to be already represented proportionally according to these standards without such additional rules.

In Ireland PR has resulted in a strange situation whereby a centre party with a large support base (Fianna Fil) has 45% of the vote but the opposition parties are extremely fragmented with the only thing that unites them being their dislike of Fianna Fail, therefore people do want a strong alternative to Fianna Fail however they differ greatly on what form that should take, thus an extremely fragmented opposition vote.

See Two-Party System: Arguments For and Against for a list of perceived advantages of proportional representation.

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Methods of Proportional Representation

There are different methods of PR, which achieve either a greater degree of proportionality or a greater degree of determinate outcome.

Party list system in a multi-member constituency

The parties each list their candidates according to that party's determination of priorities. In a closed list, voters vote for a list, not a candidate. Each party is allocated seats in proportion to the number of votes, using the ranking order on its list. In an open list, voters indicate their order of preference within the list.

Additional Member system, Mixed-Member system

Main articles: Additional Member System (Mixed Member Proportional); Parallel voting or Supplementary Member; Alternative Vote and Alternative vote top-up (Alternative Vote Plus)

The country is divided in to one-member constituencies, but a further bloc of seats are reserved for proportionality - the additional members bloc. Voters have two ballot papers: the first is a "first past the post" ballot for their local constituency. The second is a Party List ballot as above. The additional member seats are allocated in proportion to the number of party list votes. It is criticised on the grounds that a significant number of deputies are not directly answerable to constituents and are difficult to vote out of office.

Single transferable vote in a multi-member constituency

Main article (with worked examples): Single Transferable Vote

A constituency elects at least three, rarely more than five representatives. (Consequently the constituency is three to five times larger than a single member constituency in "first past the post".) The major parties may offer as many candidates as there are seats, the minor parties and independents rather fewer. Voters mark their ballot, giving their preferred ranking for some or even all the candidates. Consequently, it is the voters, rather than the party, who have final say over which candidates succeed - it is not a good system for party aparatchiks. A successful candidate must achieve one third of the preferences in a three member constituency, one fourth in a four member and so on. Only in a few cases is this achieved at the first count. For the second count, the least popular candidate is eliminated and his or her votes redistributed according to the second preference shown on them. This process continues for as many counts as are needed until all seats are filled. Although the counting process is complicated, voting is clear and most voters get at least one of their preferences elected. All deputies are answerable directly to their local constituents. Some political scientists argue that STV is more properly classified as 'semi-proportional' as there is no assurance of a proportional result at a nationwide level.

Further reading

  • John Hickman and Chris Little. "Seat/Vote Proportionality in Romanian and Spanish Parliamentary Elections" Journal of Southern Europe and the Balkans Vol. 2, No. 2, November 2000

See also

External links

  • Quantifying Representativity ( Article by Philip Kestelman
  • PR page ( from old CVD web site.
  • PR page ( from new CVD web site.
  • Electoral Reform Society (
  • Voting methods survey ( Describes 19 multi-winner systems

cs:Poměrný systém de:Proporz nl:Particratie ja:比例代表制 zh:比例代表制


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