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Ranked voting is any election voting system in which voters use a ranked (or preferential) ballot to rank choices in a sequence on the ordinal scale: 1st, 2nd, 3rd, etc. There are multiple ways in which the rankings can be counted to determine which candidate (or candidates) is (or are) elected (and different methods may choose different winners from the same set of ballots). The other major voting system is cardinal voting, where candidates are independently rated, rather than ranked.[1]

The similar term "Ranked Choice Voting" (RCV) is used by the US organization FairVote to refer to the use of ranked ballots with specific counting methods: either instant-runoff voting for single-winner elections or single transferable vote for multi-winner elections. In some locations, the term "preferential voting" is used to refer to this combination of ballot type and counting method, while in other locations this term has various more-specialized meanings.[2]

A ranked voting system collects more information from voters compared to the single-mark ballots currently used in most governmental elections, many of which use First-Past-The-Post and Mixed-Member Proportional voting systems.

There are many types of ranked voting, with several used in governmental elections. Instant-runoff voting is used in Australian state and federal elections, in Ireland for its presidential elections, and by some jurisdictions in the United States, United Kingdom, and New Zealand. A type and classification of ranked voting is called the single transferable vote, which is used for national elections in Ireland and Malta, the Australian Senate, for regional and local elections in Northern Ireland, for all local elections in Scotland, and for some local elections in New Zealand and the United States. Borda count is used in Slovenia[3] and Nauru. Contingent vote and Supplementary vote are also used in a few locations. Condorcet methods are used by private organizations and minor parties, but currently are not used in governmental elections.

Arrow's impossibility theorem and Gibbard's theorem prove that all voting systems must make trade-offs between desirable properties, such as the preference between two candidates being unaffected by the popularity of a third candidate.[4][5] Accordingly there is no consensus among academics or public servants as to the "best" electoral system.[6]

Recently, an increasing number of authors, including David Farrell, Ian McAllister and Jurij Toplak, see preferentiality as one of the characteristics by which electoral systems can be evaluated.[2][7] According to this view, all electoral methods are preferential, but to different degrees and may even be classified according to their preferentiality.[2] By this logic, cardinal voting methods such as Score voting or STAR voting are also "preferential".

Types

There are different preferential voting systems, so it is sometimes difficult to distinguish between them.

Selection of the Condorcet winner is generally considered by psephologists as the ideal election outcome for a ranked system,[8] so "Condorcet efficiency" is important when evaluating different methods of preferential voting.[9] The Condorcet winner is the one that would win every two-way contest against every other alternative.[4]

Another criterion used to gauge the effectiveness of a preferential voting system is its ability to withstand manipulative voting strategies, when voters cast ballots that do not reflect their preferences in the hope of electing their first choice. This can be rated on at least two dimensions—the number of voters needed to game the system, and the sophistication of the strategy necessary.[9]

Instant-runoff voting

Sample ballot of ranked voting using column marks

Used in national elections in Australia, this system is said to simulate a series of runoff elections. If no candidate is the first choice of more than half of the voters, then all votes cast for the candidate with the lowest number of first choices are redistributed to the remaining candidates based on who is ranked next on each ballot. If this does not result in any candidate receiving a majority, further rounds of redistribution occur.[10][11]

This method is thought to be resistant to manipulative voting as the only strategies that work against it require voters to highly rank choices they actually want to see lose. At the same time, this system fails Condorcet criterion, meaning a candidate can win even if the voters preferred a different candidate, and fails the monotonicity criterion, where ranking a candidate higher can lessen the chances he or she will be elected and vice versa. Additionally, instant-runoff voting has a lower Condorcet efficiency than similar systems when there are more than four choices.[9]

Contingent Vote

Single transferable vote

Sample ballot of ranked voting using written names

This is one of the preferential voting systems most used by countries and states. (See table below in "Use by politics".) It is used for electing multi-member constituencies. Any candidates that achieve the number of votes required for election (the "quota") are elected and their surplus votes are redistributed to the voter's next choice candidate. Once this is done, if not all places have been filled then the candidate with the lowest number of votes is eliminated, and their votes are also redistributed to the voter's next choice. This whole process is repeated until all seats are filled. This method is also called the Hare-Clark system.[12]

When single transferable vote is used for single-winner elections, it becomes equivalent to instant-runoff voting.[13]


The term Single transferable vote is sometimes used synonymously with Ranked Choice Voting. Single Transferrable Voting (STV) is categorized more clearly as a voting system designed to nearly resemble "proportional representation" through multiple constituencies rather than one. Under STV, a voter will cast a single ballot in a country or region which will elect multiple winners. Despite the difference, since both STV and RCV share similar process, in certain circumstances, they can be used interchangeable. Similar to the process involved in RCV, if there are more running candidates than available spaces on any board, then the candidate with the least amount of votes is eliminated and their votes are given to the candidate of which is the voter's back-up.

Ranked Choice Voting (RCV)

Ranked Choice Voting is a electoral selection technique used to provide assurance and security for all voters by providing them the option to rank political candidates based upon personal preference: 1st, 2nd, 3rd, and so on, rather than indicating support for only one candidate.[14] A vote is given to the voter's first preference if permissible, however, if the chosen candidate drops out of the race or is eliminated, rather than being disposed of in a regular election, the vote is transferred to the back-up or 2nd choice.

[15]Process

  1. Voters rank the candidates by preference on their ballots (most preferred candidates followed by back up candidates).
  2. The candidate with the majority (more than 50%) of 1st choice votes (the number one spot on the ballot) wins the election outright.[16]

In the circumstance that there is no majority winner (no candidate receives more than 50% of the total votes), then the race is decided by an FairVote to refer to the use of ranked ballots with specific counting methods: either instant-runoff voting for single-winner elections or single transferable vote for multi-winner elections. In some locations, the term "preferential voting" is used to refer to this combination of ballot type and counting method, while in other locations this term has various more-specialized meanings.[2]

A ranked voting system collects more information from voters compared to the single-mark ballots currently used in most governmental elections, many of which use First-Past-The-Post and Mixed-Member Proportional voting systems.

There are many types of ranked voting, with several used in governmental elections. Instant-runoff voting is used in Australian state and federal elections, in Ireland for its presidential elections, and by some jurisdictions in the United States, United Kingdom, and New Zealand. A type and classification of ranked voting is called the single transferable vote, which is used for national elections in Ireland and Malta, the Australian Senate, for regional and local elections in Northern Ireland, for all local elections in Scotland, and for some local elections in New Zealand and the United States. Borda count is used in Slovenia[3] and Nauru. Contingent vote and Supplementary vote are also used in a few locations. Condorcet methods are used by private organizations and minor parties, but currently are not used in governmental elections.

Arrow's impossibility theorem and Gibbard's theorem prove that all voting systems must make trade-offs between desirable properties, such as the preference between two candidates being unaffected by the popularity of a third candidate.[4][5] Accordingly there is no consensus among academics or public servants as to the "best" electoral system.[6]

Recently, an increasing number of authors, including David Farrell, Ian McAllister and Jurij Toplak, see preferentiality as one of the characteristics by which electoral systems can be evaluated.[2][7] According to this view, all electoral methods are preferential, but to different degrees and may even be classified according to their preferentiality.[2] By this logic, cardinal voting methods such as Score voting or STAR voting are also "preferential".

There are different preferential voting systems, so it is sometimes difficult to distinguish between them.

Selection of the Condorcet winner is generally considered by psephologists as the ideal election outcome for a ranked system,[8] so "Condorcet efficiency" is important when evaluating different methods of preferential voting.[9] The Condorcet winner is the one that would win every two-way contest against every other alternative.[4]

Another criterion used to gauge the effectiveness of a preferential voting system is its ability to withstand manipulative voting strategies, when voters cast ballots that do not reflect their preferences in the hope of electing their first choice. This can be rated on at least two dimensions—the number of voters needed to game the system, and the sophistication of the strategy necessary.[9]

Instant-runoff voting

Sample ballot of ranked voting using column marks

Used in national elections in Australia, this system is said to simulate a series of runoff elections. If no candidate is the first choice of more than half of the voters, then all votes cast for the candidate with the lowest number of first choices are redistributed to the remaining candidates based on who is ranked next on each ballot. If this does not result in any candidate receiving a majority, further rounds of redistribution occur.[10][11]

This method is thought to be resistant to manipulative voting as the only strategies that work against it require voters to highly rank choices they actually want to see lose. At the same time, this system fails Condorcet criterion, meaning a candidate can win even if the voters preferred a different candidate, and fails the monotonicity criterion, where ranking a candidate higher can lessen the chances he or she will be elected and vice versa. Additionally, instant-runoff voting has a lower Condorcet efficiency than similar systems when there are more than four choices.[9]

Contingent Vote

Single transferable vote

Condorcet winner is generally considered by psephologists as the ideal election outcome for a ranked system,[8] so "Condorcet efficiency" is important when evaluating different methods of preferential voting.[9] The Condorcet winner is the one that would win every two-way contest against every other alternative.[4]

Another criterion used to gauge the effectiveness of a preferential voting system is its ability to withstand manipulative voting strategies, when voters cast ballots that do not reflect their preferences in the hope of electing their first choice. This can be rated on at least two dimensions—the number of voters needed to game the system, and the sophistication of the strategy necessary.[9]

Used in national elections in Australia, this system is said to simulate a series of runoff elections. If no candidate is the first choice of more than half of the voters, then all votes cast for the candidate with the lowest number of first choices are redistributed to the remaining candidates based on who is ranked next on each ballot. If this does not result in any candidate receiving a majority, further rounds of redistribution occur.[10][11]

This method is thought to be resistant to manipulative voting as the only strategies that work against it require voters to highly rank choices they actually want to see lose. At the same time, this system fails Condorcet criterion, meaning a candidate can win even if the voters preferred a different candidate, and fails the monotonicity criterion, where ranking a candidate higher can lessen the chances he or she will be elected and vice versa. Additionally, instant-runoff voting has a lower Condorcet efficiency than similar systems when there are more than four choices.[9]

Contingent Vote

Ranked Choice Voting is a electoral selection technique used to provide assurance and security for all voters by providing them the option to rank political candidates based

When single transferable vote is used for single-winner elections, it becomes equivalent to instant-runoff voting.[13]


The term Single transferable vote is sometimes used synonymously with Ranked Choice Voting. Single Transferrable Voting (STV) is categorized more clearly as a voting system designed to nearly resemble "proportional representation" through multiple constituencies rather than one. Under STV, a voter will cast a single ballot in a country or region which will elect multiple winners. Despite the difference, since both STV and RCV share similar process, in certain circumstances, they can be used interchangeable. Similar to the process involved in RCV, if there are more running candidates than available spaces on any board, then the candidate with the least amount of votes is eliminated and their votes are given to the candidate of which is the voter's back-up.

Ranked Choice Voting is a electoral selection technique used to provide assurance and security for all voters by providing them the option to rank political candidates based upon personal preference: 1st, 2nd, 3rd, and so on, rather than indicating support for only one candidate.[14] A vote is given to the voter's first preference if permissible, however, if the chosen candidate drops out of the race or is eliminated, rather than being disposed of in a regular election, the vote is transferred to the back-up or 2nd choice.

[15]Process

  1. In the process of an Instant-runoff, if no candidate receives a majority of each voter's top choice, then the candidate with the fewest number of votes is eliminated from the race and voters.
  2. That being said, 1st preference votes for the eliminated candidate will have their votes count for the next choice.
  3. A new vote is counted adjusted usi

    Instant Runoff Voting is similar to Single Transferable Voting in that with IRV, the goal is a majority representation of total votes in a district, rather than proportional representation of all voting blocks/districts.

    Related Terminology

    The term Instant-runoff is used in two contexts.

    1. As a synonym for Ranked Choice Voting
    2. As a description of Ranked Choice Voting processes specifically around voting circumstances where no voter holds such a majority. It is essentially a contingency process within another process- only used when necessary. (Used in single winner elections only)[18]

    Condorcet method

    Borda is a positional system in which ballots are counted by assigning a point value to each place in each voter's ranking of the candidates, and the choice with the largest number of points overall is elected. This method is named after its inventor, French mathematician Jean-Charles de Borda.[4] Instead of selecting a Condorcet winner, this system may select a choice that reflects an average of the preferences of the constituency.[citation needed]

    The Borda count does not exhibit Jean-Charles de Borda.[4] Instead of selecting a Condorcet winner, this system may select a choice that reflects an average of the preferences of the constituency.[citation needed]

    The Borda count does not exhibit independence of irrelevant alternatives[4] or independence of clones meaning the outcome it selects is dependent on the oth

    The Borda count does not exhibit independence of irrelevant alternatives[4] or independence of clones meaning the outcome it selects is dependent on the other choices present. In large scale elections, the Borda Count is only weakly manipulated by adding candidates, called clones, whose views are similar to the preferred candidate's, but in a small committee election it can more easily manipulated. An example of this strategy can be seen in Kiribati's 1991 presidential nomination contest.[21]

    Some examples of RCV elections are shown below. The first table shows the process of RCV and the second demonstrates how Instant Runoff Voting plays a role in these elections. These examples have been taken from Ballotpedia and represents hypothetical situations to demonstrate a process and clarify a concept. [22]

    Example 1:

    Raw first-preference vote in political race
    Candidate First-Preference Votes Percent outcome
    Candidate A 475 46.34%
    Candidate B 300 29.27%
    Candidate C 175 17.07%
    Candidate D 75 7.32%

    Hypothetically speaking, there are four candidates running for a political election, the figure about shows the first

    Hypothetically speaking, there are four candidates running for a political election, the figure about shows the first preference votes based on each candidate and the accompanied percentages of total votes.

    According to the results of the first election, no candidate received an outright majority, with the largest being candidate A with 46.34%. Based on Instant Runoff Election strategy, the candidate with the lowest total votes is to be eliminated, so in this case, candidate D is eliminated. As follows, the first-preference votes for the eliminated candidate are given to voter back-ups. For the sake of the example, assume that of the total 75 votes Candidate D received, Candidate A was listed as their second choice by 50 voters, and Candidate B was listed as a second preference by 25 of the voters.

    Example 2:

    Pros<

    Advocates of Ranked Choice Voting argue that RCV promotes majority support: the voting process continues until the winner is selected using a majority of votes, thus gaining support and favor over a greater majority of people. Subsequently, RCV provides more choice for voters over candidates they choose, potentially, minimizing strategic voting in which a voter may feel compelled to vote for the lesser of two evils." For candidates that run a negative campaigning strategy, verbally harming and demeaning their running-mates, they may see a decline in voter turn out due to this behavior that some voters might frown upon. Compared to running primary elections, in order to decrease the amount of candidates running for a particular position, a ranked choice voting system may cost less to run due to the requirement of only one election, rather than multiple primaries or run-off elections to narrow down the field. [23]

    Cons

    Some may also agree with the saying "if it's not broke, don't fix it" in saying that the concept and practice of Ranked Choice Voting is rather new and some people dislike change, possibly causing them to dislike the system and not participate. Because RCV is a new concept, it may also require a country to implement a nationwide educat

    Some may also agree with the saying "if it's not broke, don't fix it" in saying that the concept and practice of Ranked Choice Voting is rather new and some people dislike change, possibly causing them to dislike the system and not participate. Because RCV is a new concept, it may also require a country to implement a nationwide education system on this novel voting system in order to ensure citizens know how to vote properly. Among other arguments is the possibility that the ballots and counting processes will be more expensive and prone to user error. As such, RCV will either require a computerized counting system or a hand counting system which possibly could be more labor intensive than that of Cardinal Voting. While utilizing a computerized counting system, some say it is still necessary to hold on to the paper ballots so that election recounts can still be performed, minimizing error and holding a greater validity of results. [24]

    The “Vetting Process”
    preference voting patterns will be unique to individual voters.[26][27] For example, in the 2002 Irish general election, the electronic votes were published for the Dublin North constituency.[28] There were 12 candidates and almost 44,000 votes cast. The most common pattern (for the three candidates from one party in a particular order) was chosen by only 800 voters, and more than 16,000 patterns were chosen by just one voter each.

    The number of possible complete rankings with no ties is the factorial of the number of candidates, N; but if ties are allowed freely, it is equal to the corresponding ordered Bell number and is asymptotic to

    &#

    The number of possible complete rankings with no ties is the factorial of the number of candidates, N; but if ties are allowed freely, it is equal to the corresponding ordered Bell number and is asymptotic to

    In the case common to instant-runoff voting in which no ties are allowed, except for unranked candidates who are tied for last place on a ballot, the number of possible rankings for N candidates is precisely