Plurality-Majority		Semi-PR		Proportional Representation
FPTP UK, India		Parallel Japan, Russia		STV Ireland, Malta
Block Vote Palestine, Maldives		SNTV Jordan, Vanuatu		MMP New Zealand, Germany
Alternative Vote Australia, Nauru				List PR South Africa
Two-Round France, Mali

A. Plurality-Majority Systems

The four types of plurality-majority systems comprise two plurality systems, First Past the Post and the Block Vote, and two majority systems, the Alternative Vote and the Two-Round System.

First Past the Post (FPTP) is the world’s most commonly-used electoral system. In a First Past the Post system, contests are held in single-member districts, and the winner is the candidate with the most votes, but not necessarily an absolute majority of the votes. Countries which use this system include the United Kingdom, the United States, India, Canada, and most countries which were once part of the British Empire.

The Block Vote (BV) is the application of FPTP in multi- rather than single-member districts. Voters have as many votes as there are seats to be filled, and the highest-polling candidates fill the positions regardless of the percentage of the votes they actually achieve. This system is used in some parts of Asia and the Middle East.

The Alternative Vote (AV) enables electors to rank the candidates in the order of their choice, by marking a “1” for their favourite candidate, “2” for their second-choice, “3” for their third choice, and so on. If no candidate has over 50 per cent of first-preferences, lower order preference votes are transferred until a majority winner emerges. This system is used in Australia and some other South Pacific countries.

The other type of majority system, the Two-Round System (TRS), takes place in two rounds, often a week or a fortnight apart. The first round is conducted in the same way as a normal FPTP election. If no candidate receives an absolute majority in the first round, then a second round of voting is conducted between the highest-polling candidates from the first round, and the winner of this round is declared elected. This system is used in France, Central Asia and current or former French colonies.

B. Semi-Proportional Systems

Semi-PR systems are those which inherently translate votes cast into seats won in a way that falls somewhere in between the proportionality of PR systems and the majoritarianism of plurality-majority systems. The two Semi-PR electoral systems used for legislative elections are the Single Non-Transferable Vote (SNTV), and Parallel (or mixed) systems.

In SNTV elections, each elector has one vote but there are several seats in the district to be filled, and the candidates with the highest number of votes fill these positions. This system is used today only in Jordan and Vanuatu. Parallel systems use both PR lists and plurality-majority districts running side-by-side (hence the term parallel). Part of the parliament is elected by proportional representation, part by some type of plurality or majority method.

C. Proportional Representation Systems

The rationale underpinning all Proportional Representation (PR) systems is to consciously reduce the disparity between a party’s share of the national votes and its share of the parliamentary seats. Proportionality is often seen as being best achieved by the use of party lists, where political parties present lists of candidates to the voters on a national or regional basis, and where there are many members to be elected from each district, thus enabling the representation of even small minorities. Lists can be “open” or “closed”, depending upon whether voters can specify their favoured candidate(s) within a given party list (“open” lists), or whether they can only vote for a party without influencing which party candidates are elected (“closed” lists).

List PR systems are the most common type of proportional representation electoral systems. Most forms of List PR are held in large, multi-member districts which maximize proportionality. List PR requires each party to present a list of candidates to the electorate. Electors vote for a party rather than a candidate; and parties receive seats in proportion to their overall share of the national vote. Winning candidates are taken from the lists in order of their respective position. This system is widely used in continental Europe, Latin America and southern Africa.

Mixed Member Proportional (MMP) systems, as used in Germany, New Zealand, Bolivia, Italy, Mexico, Venezuela, and Hungary, attempt to combine the positive attributes of both majoritarian and PR electoral systems. A proportion of the parliament is elected by plurality-majority methods, usually from single-member districts, while the remainder is constituted by PR lists, with the PR seats being used to compensate for any disproportionality produced by the district seat results.

The Single Transferable Vote uses multi-member districts, with voters ranking candidates in order of preference on the ballot paper in the same manner as the Alternative Vote. After the total number of first-preference votes are tallied, the count then begins by establishing the “quota” of votes required for the election of a single candidate. Any candidate who has more first preferences than the quota is immediately elected. If no-one has achieved the quota, the candidate with the lowest number of first preferences is eliminated, with his or her second preferences being redistributed to the candidates left in the race. At the same time, the surplus votes of elected candidates (that is, those votes above the quota) are redistributed according to the second preferences on the ballot papers until all seats for the constituency are filled.

Source: Reynolds, Andrew and Ben Reilly et. al. 1997. The International IDEA Handbook of Electoral System Design. Stockholm: International IDEA.