Single non-transferable vote
Encyclopedia
The single non-transferable vote or SNTV is an electoral system used in multi-member constituency elections.
C, D and E are the winning candidates.
This breaks down by party as:
Party Y has more votes than Party Z, but fewer seats because of an inefficient spread of votes across the candidates. If either party had risked trying to win all three seats, then Party X would have a higher chance of winning a seat, in the event of an uneven distribution of votes.
when political parties have accurate information about their relative levels of electoral support, and nominate candidates in accordance with their respective level of electoral support. If there are n candidates to be elected, Candidate A can guarantee being elected by receiving one more than 1/(n+1) of the votes (the Droop quota
), because n other candidates cannot all receive more than Candidate A. It can become very difficult for parties to receive representation proportional to their strength, because they are forced to judge their strength prior to deciding how many candidates to field (strategic nomination
). If they field too many, their supporters votes might be split
across too many candidates, evenly diluting their share to the point where they all lose to a less diluted opposing party. If the party fields too few candidates, they might not win seats proportional to their hypothetical true level of support and excess votes would be wasted on their winning candidates.
The relative risks of strategic nomination are not the same for parties in other positions of electoral success. A large party with a majority of seats would have much more to lose from the split vote effect than to gain from avoiding the wasted vote effect, and so would likely decide to err on the side of fielding fewer candidates. A small party with little representation would be more risk-tolerant and err on the side of too many candidates, potentially gaining seats greater than their proportion of the electorate by winning with narrower margins of victory than the candidates from larger parties.
SNTV electoral systems, like proportional electoral systems generally, typically produce more proportional electoral outcomes as the size of the electoral districts (number of seats in each constituency) increases.
in a single non-transferable vote system is large. Receiving only one vote, the rational voter must only vote for a candidate that has a chance of winning, but will not win by too great a margin, thus taking votes away from party colleagues. This also creates opportunities for tactical nominations, with parties nominating candidates similar to their opponents' candidates in order to split the vote.
SNTV can also result in complicated intra-party dynamics because in a SNTV system, a candidate must not only run against candidates from the other party, but must also run against candidates from their own party.
Because running on issues may lead to a situation in which a candidate becomes too popular and therefore draws votes away from other allied candidates, it has been argued that SNTV encourages legislators to join factions which consist of patron-client relationships in which a powerful legislator can apportion votes to his or her supporters. It has been argued that many of the characteristics of the Kuomintang
in Taiwan and the Liberal Democratic Party of Japan have arisen on account of this.
In addition, parties must ensure that their supporters evenly distribute their votes among the party's candidates. Historically, in Taiwan
, the Kuomintang
did this by sending members a letter telling them which candidate to vote for. With the Democratic Progressive Party
, vote sharing is done informally, as members of a family or small group will coordinate their votes. The New Party
had a surprisingly effective system by asking party supporters to vote for the candidate that corresponded to their birthdate. This led to a system of vote allocation
which had been adopted by all parties for the 2004 ROC Legislative elections.
, Jordan
and for the elections to the upper house of Indonesia
and for the senate of Thailand under the 1997 constitution.
, where SNTV is known as at-large representation ("representación por acumulación" in Spanish), political parties vary the ballot order of their candidates across electoral divisions, in order to ensure each candidate has a roughly equal chance of being elected. Since most voters choose the candidates placed at the top of their party lists on the ballots they receive, at-large candidates from the same party usually obtain approximately equal vote totals.
The two major Puerto Rican political parties, the Popular Democratic Party
and the New Progressive Party
, usually nominate six candidates for each chamber, while the much smaller Puerto Rican Independence Party
runs single-candidate slates for both the Senate and the House of Representatives. The overall distribution of legislative seats is largely determined by the results for the sixteen Senate and forty House district seats, elected by plurality voting
.
, South Korea
and the Republic of China
(Taiwan
), but its use has been discontinued for the most part. It is still used in Japan for some seats in the House of Councillors
(Sangi-in), prefectural assemblies and municipal assemblies, and in Taiwan for the six aboriginal seats in the Legislative Yuan
(national legislature), as well as local assemblies.
In Taiwan, the party structure was further complicated by the fact that while members of the Legislative Yuan
were elected by SNTV, executive positions were (and still are) elected by a First Past the Post. This created a party system in which smaller factionalized parties, which SNTV promotes, have formed two large coalitions that resembles the two party system which First Past the Post rewards
. Starting with the 2008 legislative elections, the SNTV system was discarded in favor of a mixed single member district (SMD) with proportional representation based on national party votes, similar to Japan.
system with party lists and Hare quota
, in practice political parties would field multiple lists in the same constituency. For example, the Democratic Party
fielded three separate lists in the eight-seat New Territories West constituency in the 2008 election, aiming to win three seats (which they ended up with two winners). Split list or split tickets is done in order to win more seats with fewer votes, since the first candidate on each list would require less than the Hare quota to get a seat. Supporters are asked to split their votes among the lists of the same party, usually along geographical location of residence.
Voting
In any election, each voter casts one vote for one candidate in a multi-candidate race for multiple offices. Posts are filled by the candidates with the most votes. In a three-seat constituency, the three candidates receiving the largest numbers of votes would win office.Example
There are three seats to be filled and five candidates: A, B, C, D and E.| Votes | Candidate | Party |
| 819 | A | X |
| 1,804 | B | Y |
| 1,996 | C | Z |
| 1,999 | D | Z |
| 2,718 | E | Y |
C, D and E are the winning candidates.
This breaks down by party as:
| Party | Votes | Percent | Seats |
| Y | 4,639 | 51 | 1 |
| Z | 3,995 | 44 | 2 |
| X | 819 | 9 | 0 |
Party Y has more votes than Party Z, but fewer seats because of an inefficient spread of votes across the candidates. If either party had risked trying to win all three seats, then Party X would have a higher chance of winning a seat, in the event of an uneven distribution of votes.
Proportional representation
SNTV can result in proportional representationProportional representation
Proportional representation is a concept in voting systems used to elect an assembly or council. PR means that the number of seats won by a party or group of candidates is proportionate to the number of votes received. For example, under a PR voting system if 30% of voters support a particular...
when political parties have accurate information about their relative levels of electoral support, and nominate candidates in accordance with their respective level of electoral support. If there are n candidates to be elected, Candidate A can guarantee being elected by receiving one more than 1/(n+1) of the votes (the Droop quota
Droop Quota
The Droop quota is the quota most commonly used in elections held under the Single Transferable Vote system. It is also sometimes used in elections held under the largest remainder method of party-list proportional representation . In an STV election the quota is the minimum number of votes a...
), because n other candidates cannot all receive more than Candidate A. It can become very difficult for parties to receive representation proportional to their strength, because they are forced to judge their strength prior to deciding how many candidates to field (strategic nomination
Strategic nomination
Strategic nomination is the manipulation of an election through its candidate set...
). If they field too many, their supporters votes might be split
Split vote
A split vote is normally used synonymously with "deadlocked", "hung", or "evenly split" vote. It indicates a vote in which no decision can be made, as neither side has the majority....
across too many candidates, evenly diluting their share to the point where they all lose to a less diluted opposing party. If the party fields too few candidates, they might not win seats proportional to their hypothetical true level of support and excess votes would be wasted on their winning candidates.
The relative risks of strategic nomination are not the same for parties in other positions of electoral success. A large party with a majority of seats would have much more to lose from the split vote effect than to gain from avoiding the wasted vote effect, and so would likely decide to err on the side of fielding fewer candidates. A small party with little representation would be more risk-tolerant and err on the side of too many candidates, potentially gaining seats greater than their proportion of the electorate by winning with narrower margins of victory than the candidates from larger parties.
SNTV electoral systems, like proportional electoral systems generally, typically produce more proportional electoral outcomes as the size of the electoral districts (number of seats in each constituency) increases.
Potential for tactical voting
The potential for tactical votingTactical voting
In voting systems, tactical voting occurs, in elections with more than two viable candidates, when a voter supports a candidate other than his or her sincere preference in order to prevent an undesirable outcome.It has been shown by the Gibbard-Satterthwaite theorem that any voting method which is...
in a single non-transferable vote system is large. Receiving only one vote, the rational voter must only vote for a candidate that has a chance of winning, but will not win by too great a margin, thus taking votes away from party colleagues. This also creates opportunities for tactical nominations, with parties nominating candidates similar to their opponents' candidates in order to split the vote.
SNTV can also result in complicated intra-party dynamics because in a SNTV system, a candidate must not only run against candidates from the other party, but must also run against candidates from their own party.
Because running on issues may lead to a situation in which a candidate becomes too popular and therefore draws votes away from other allied candidates, it has been argued that SNTV encourages legislators to join factions which consist of patron-client relationships in which a powerful legislator can apportion votes to his or her supporters. It has been argued that many of the characteristics of the Kuomintang
Kuomintang
The Kuomintang of China , sometimes romanized as Guomindang via the Pinyin transcription system or GMD for short, and translated as the Chinese Nationalist Party is a founding and ruling political party of the Republic of China . Its guiding ideology is the Three Principles of the People, espoused...
in Taiwan and the Liberal Democratic Party of Japan have arisen on account of this.
In addition, parties must ensure that their supporters evenly distribute their votes among the party's candidates. Historically, in Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, the Kuomintang
Kuomintang
The Kuomintang of China , sometimes romanized as Guomindang via the Pinyin transcription system or GMD for short, and translated as the Chinese Nationalist Party is a founding and ruling political party of the Republic of China . Its guiding ideology is the Three Principles of the People, espoused...
did this by sending members a letter telling them which candidate to vote for. With the Democratic Progressive Party
Democratic Progressive Party
The Democratic Progressive Party is a political party in Taiwan, and the dominant party in the Pan-Green Coalition. Founded in 1986, DPP is the first meaningful opposition party in Taiwan. It has traditionally been associated with strong advocacy of human rights and a distinct Taiwanese identity,...
, vote sharing is done informally, as members of a family or small group will coordinate their votes. The New Party
New Party (Republic of China)
The New Party, formerly the Chinese New Party , is a centre-right conservative political party in the Republic of China , and part of the pan-blue coalition....
had a surprisingly effective system by asking party supporters to vote for the candidate that corresponded to their birthdate. This led to a system of vote allocation
Vote allocation
Vote allocation is a system of tactical voting used in the Republic of China on Taiwan from the late-1990s until 2004, after which the voting system is to be changed from single non-transferable vote to a parallel voting system. In this system, voters are asked to vote for a party candidate based...
which had been adopted by all parties for the 2004 ROC Legislative elections.
Usage
SNTV is used for legislative elections in AfghanistanElections in Afghanistan
This article gives information on elections in Afghanistan.Though Afghanistan has had democratic elections throughout the 20th century, the election institutions have varied as changes in regimes have disrupted political continuity...
, Jordan
Elections in Jordan
Jordan elects a legislature on the national level. The National Assembly has two chambers. The Chamber of Deputies has 110 members, 104 elected for a four-year term in single-seat constituencies and 6 female members by a special electoral college. Of the 110 seats, Christians are reserved 9 seats...
and for the elections to the upper house of Indonesia
Elections in Indonesia
Elections in Indonesia have taken place since 1955. At a national level, Indonesian people elect a head of state – the president – and a legislature...
and for the senate of Thailand under the 1997 constitution.
Puerto Rico
In Puerto RicoPuerto Rico
Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...
, where SNTV is known as at-large representation ("representación por acumulación" in Spanish), political parties vary the ballot order of their candidates across electoral divisions, in order to ensure each candidate has a roughly equal chance of being elected. Since most voters choose the candidates placed at the top of their party lists on the ballots they receive, at-large candidates from the same party usually obtain approximately equal vote totals.
The two major Puerto Rican political parties, the Popular Democratic Party
Popular Democratic Party of Puerto Rico
The Popular Democratic Party of Puerto Rico is a political party that supports Puerto Rico's right to self-determination and sovereignty, through the enhancement of Puerto Rico's current status as a commonwealth....
and the New Progressive Party
New Progressive Party of Puerto Rico
The New Progressive Party of Puerto Rico is a political party that advocates for Puerto Rico's admission to the United States of America as the 51st state...
, usually nominate six candidates for each chamber, while the much smaller Puerto Rican Independence Party
Puerto Rican Independence Party
The Puerto Rican Independence Party is a Puerto Rican political party that campaigns for the independence of Puerto Rico from United States suzerainty....
runs single-candidate slates for both the Senate and the House of Representatives. The overall distribution of legislative seats is largely determined by the results for the sixteen Senate and forty House district seats, elected by plurality voting
Plurality voting system
The plurality voting system is a single-winner voting system often used to elect executive officers or to elect members of a legislative assembly which is based on single-member constituencies...
.
Japan, South Korea, and Taiwan
SNTV was once used to elect the parliaments of JapanJapan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, South Korea
South Korea
The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...
and the Republic of China
Republic of China
The Republic of China , commonly known as Taiwan , is a unitary sovereign state located in East Asia. Originally based in mainland China, the Republic of China currently governs the island of Taiwan , which forms over 99% of its current territory, as well as Penghu, Kinmen, Matsu and other minor...
(Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
), but its use has been discontinued for the most part. It is still used in Japan for some seats in the House of Councillors
House of Councillors
The is the upper house of the Diet of Japan. The House of Representatives is the lower house. The House of Councillors is the successor to the pre-war House of Peers. If the two houses disagree on matters of the budget, treaties, or designation of the prime minister, the House of Representatives...
(Sangi-in), prefectural assemblies and municipal assemblies, and in Taiwan for the six aboriginal seats in the Legislative Yuan
Legislative Yuan
The Legislative Yuan is the unicameral legislature of the Republic of China .The Legislative Yuan is one of the five branches of government stipulated by the Constitution of the Republic of China, which follows Sun Yat-sen's Three Principles of the People...
(national legislature), as well as local assemblies.
In Taiwan, the party structure was further complicated by the fact that while members of the Legislative Yuan
Legislative Yuan
The Legislative Yuan is the unicameral legislature of the Republic of China .The Legislative Yuan is one of the five branches of government stipulated by the Constitution of the Republic of China, which follows Sun Yat-sen's Three Principles of the People...
were elected by SNTV, executive positions were (and still are) elected by a First Past the Post. This created a party system in which smaller factionalized parties, which SNTV promotes, have formed two large coalitions that resembles the two party system which First Past the Post rewards
Duverger's law
In political science, Duverger's law is a principle which asserts that a plurality rule election system tends to favor a two-party system. This is one of two hypotheses proposed by Duverger, the second stating that “the double ballot majority system and proportional representation tend to...
. Starting with the 2008 legislative elections, the SNTV system was discarded in favor of a mixed single member district (SMD) with proportional representation based on national party votes, similar to Japan.
Hong Kong, China
Although the electoral system for half of the seats of the Legislative Council of the territory is nominally a proportional representationProportional representation
Proportional representation is a concept in voting systems used to elect an assembly or council. PR means that the number of seats won by a party or group of candidates is proportionate to the number of votes received. For example, under a PR voting system if 30% of voters support a particular...
system with party lists and Hare quota
Hare quota
The Hare quota is a formula used under some forms of the Single Transferable Vote system and the largest remainder method of party-list proportional representation...
, in practice political parties would field multiple lists in the same constituency. For example, the Democratic Party
Democratic Party (Hong Kong)
The Democratic Party is a pro-democracy political party in Hong Kong. It was established on 2 October 1994. The party is currently the second largest party in the Legislative Council, headed by Chairman Albert Ho Chun-yan and, following the November 2008 merger with the Frontier, had around 745...
fielded three separate lists in the eight-seat New Territories West constituency in the 2008 election, aiming to win three seats (which they ended up with two winners). Split list or split tickets is done in order to win more seats with fewer votes, since the first candidate on each list would require less than the Hare quota to get a seat. Supporters are asked to split their votes among the lists of the same party, usually along geographical location of residence.
See also
- Single transferable voteSingle transferable voteThe single transferable vote is a voting system designed to achieve proportional representation through preferential voting. Under STV, an elector's vote is initially allocated to his or her most preferred candidate, and then, after candidates have been either elected or eliminated, any surplus or...
- Runoff votingTwo-round systemThe two-round system is a voting system used to elect a single winner where the voter casts a single vote for their chosen candidate...
External links
- A Handbook of Electoral System Design from International IDEA
- ACE Project—Expert site providing encyclopedia on Electoral Systems and Management, country by country data, a library of electoral materials, latest election news, the opportunity to submit questions to a network of electoral experts, and a forum to discuss all of the above
- Electoral Design Reference Materials from the ACE Project