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STAR voting is an electoral system for single-seat elections. [1] [2] The name (an allusion to star ratings) stands for "Score then Automatic Runoff", referring to the fact that this system is a combination of score voting, to pick two finalists with the highest total scores, followed by an "automatic runoff" in which the finalist who is preferred on more ballots wins. It is a type of cardinal voting electoral system.
In STAR, voters are given a score ballot (or ratings ballot) on which each voter scores candidates with a number from 0 up to 5, with 0 representing "worst" and 5 representing "best."
The scores for each candidate are then summed, and the two highest-scored candidates are selected as finalists.
In the automatic runoff round, the finalist who was given a higher score on a greater number of ballots is selected as the winner.
The concept was first proposed in October 2014 by Mark Frohnmayer, and was initially called score runoff voting (SRV). [3] The runoff step was introduced in order to reduce strategic incentives in ordinary score voting, such as bullet voting and tactical maximization. [4] STAR is intended to be a hybrid between (rated) score voting and (ranked) instant runoff voting. [5] [6]
The first movement to implement STAR voting was centered in Oregon, [7] [8] with chapters in Eugene, Portland, Salem, Astoria, and Ashland. [9] In July 2018, supporters submitted over 16,000 signatures for a ballot initiative in Lane County, Oregon, putting Measure 20-290 on the November 2018 ballot. [1] [10] [11] [12] This ballot measure did not pass, with 47.6% of voters voting yes, and 52.4% of voters voting no. [13] [14]
In 2019, the Multnomah County Democratic Party adopted STAR for all internal elections. [15] [16]
A 2020 ballot initiative for the city of Eugene (in which a 54% majority had supported the 2018 county initiative) was attempted, as well as a second attempt at Lane County, [17] and an initiative in Troutdale, Oregon. [18] On July 27, 2020, after the Eugene City Council deadlocked at 4-4 on a vote to refer a measure allowing STAR voting to be used in city elections to the November 2020 ballot, Eugene Mayor Lucy Vinis cast the deciding vote against the referral, meaning that no Eugene ballot measure would be held in 2020. [19]
The Independent Party of Oregon used STAR voting in their 2020 primary election. [20] [21] [22] [23] The Democratic Party of Oregon used STAR Voting for their elections for delegates to the 2020 Democratic convention. [23] In 2022, the Libertarian Party of Oregon authorized STAR voting for its internal elections starting in 2023. [24]
Suppose that Tennessee is holding an election on the location of its capital. The population is concentrated around four major cities. All voters want the capital to be as close to them as possible. The options are:
The preferences of each region's voters are:
42% of voters Far-West | 26% of voters Center | 15% of voters Center-East | 17% of voters Far-East |
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Suppose that 100 voters each decided to score from 0 to 5 stars each city such that their most liked choice got 5 stars, and least liked choice got 0 stars, with the intermediate choices getting an amount proportional to their relative distance.
Voter from/ City Choice | Memphis | Nashville | Chattanooga | Knoxville | Total |
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Memphis | 210 (42 × 5) | 0 (26 × 0) | 0 (15 × 0) | 0 (17 × 0) | 210 |
Nashville | 84 (42 × 2) | 130 (26 × 5) | 45 (15 × 3) | 34 (17 × 2) | 293 |
Chattanooga | 42 (42 × 1) | 52 (26 × 2) | 75 (15 × 5) | 68 (17 × 4) | 237 |
Knoxville | 0 (42 × 0) | 26 (26 × 1) | 45 (15 × 3) | 85 (17 × 5) | 156 |
The top-two frontrunners are Nashville and Chattanooga. Of the two, Nashville is preferred by 68% (42+26) to 32% (15+17) of voters, so Nashville, the capital in real life, likewise wins in the example.
For comparison, note that traditional first-past-the-post would elect Memphis, even though most citizens consider it the worst choice, because 42% is larger than any other single city. Instant-runoff voting would elect the 2nd-worst choice (Knoxville), because the central candidates would be eliminated early. Under score voting, Nashville would have won, since it had the highest score in the first round. In approval voting, with each voter selecting their top two cities, Nashville would also win because of the significant boost from Memphis residents. A two-round system would have a runoff between Memphis and Nashville, where Nashville would win.
In this particular case, there is no way for any single city of voters to get a better outcome through tactical voting. However, Chattanooga and Knoxville voters combined could vote strategically to make Chattanooga win; while Memphis and Nashville voters could defend against that strategy and ensure Nashville still won by strategically giving Nashville a higher rating and/or Chattanooga and Knoxville lower ratings.
Tie votes in STAR Voting are rare, but as with any voting method they can occur, especially in elections without many voters. In most cases, ties in STAR voting can be broken by referring back to the ballots themselves for either the Scoring or Runoff round. Ties in the Scoring round are broken in favor of the candidate who was preferred by more voters. Ties in the Runoff round are broken in favor of the candidate who was scored higher. Ties which cannot be broken as above are considered a true tie. [25]
Unlike ranked voting systems, STAR voting allows voters to express preferences of varying strengths, though unlike Score voting, it does not take voters' strength of preference into account in 2-candidate elections. [26]
STAR voting satisfies the monotonicity criterion, i.e. raising your vote's score for a candidate can never hurt their chances of winning, and lowering it can never help their chances. [27] [28] It also satisfies the resolvability criterion (in both Tideman and Woodall's versions).[ citation needed ]
There are a number of other voting system criteria it does not fully satisfy. These include the majority criterion, as it can happen that a candidate does not make it to the runoff, even though he is the first preference of a majority. [29] It does not satisfy the mutual majority criterion, although the more candidates there are in the mutual majority set, the greater the chances that at least one of them is among the two finalists in the runoff, in which case one of them will win. It does not always satisfy reversal symmetry (though it only violates it for exactly three candidates).
It also violates participation, consistency; and independence of clones (where any clones of the highest rated candidate may receive almost the same rating and enter the runoff, ahead of the second most popular non-clone).
It does not satisfy the later-no-harm criterion, meaning that giving a positive rating to a less-preferred candidate can cause a more-preferred candidate to lose. [30]
FairVote, an organization that promotes the use of instant-runoff voting, argues that STAR's failure of the majority criterion and the later-no-harm criterion is problematic. [31] STAR advocates have responded, [32] noting that STAR satisfies a relaxed version of the majority criterion, [33] and never elects a Condorcet loser, and that the system better balances the competing, incompatible favorite betrayal and later-no-harm criteria, resulting in superior voter satisfaction, as demonstrated by simulations in which STAR performs better than many other methods, including Instant Runoff voting. [30]
a two-phase, one-election hybrid of the Rating and Ranked Choice categories
STAR Voting is the new and improved hybrid of RCV and Score Voting
20-290 Lane County Adopts STAR Voting: Yes 74408, No 82157, Total 156565
STAR is monotonic, IRV is not.
STAR Voting actually fails both Later No Harm and The Favorite Betrayal Criterion - but hear us out! This is actually also desirable. ... We believe it is better for a system to fail two opposing criteria and in doing so mitigate the ways in which it fails both
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: CS1 maint: numeric names: authors list (link)Approval voting is an electoral system in which voters can select any number of candidates instead of selecting only one.
Score voting or range voting is an electoral system for single-seat elections, in which voters give each candidate a score, the scores are added, and the candidate with the highest total is elected. It has been described by various other names including evaluative voting, utilitarian voting, interval measure voting, point-sum voting, ratings summation, 0-99 voting, and average voting. It is a type of cardinal voting electoral system that aims to approximate the utilitarian social choice rule.
A Condorcet method is an election method that elects the candidate who wins a majority of the vote in every head-to-head election against each of the other candidates, whenever there is such a candidate. A candidate with this property, the pairwise champion or beats-all winner, is formally called the Condorcet winner. The head-to-head elections need not be done separately; a voter's choice within any given pair can be determined from the ranking.
Copeland's method, also called Llull's method or round-robin voting, is a ranked-choice voting system based on scoring pairwise wins and losses.
The monotonicity criterion, also called positive weight, is a principle of social choice theory that says voters should never have a negative effect on an election's results. In other words, increasing a winning candidate's grade should not cause them to lose.
Bucklin voting is a class of voting methods that can be used for single-member and multi-member districts. As in highest median rules like the majority judgment, the Bucklin winner will be one of the candidates with the highest median ranking or rating. It is named after its original promoter, the Georgist politician James W. Bucklin of Grand Junction, Colorado, and is also known as the Grand Junction system.
Ranked pairs, sometimes called the Tideman method, is a tournament-style system of ranked-choice voting first proposed by Nicolaus Tideman in 1987.
The mutual majority criterion, also known as majority for solid coalitions or the generalized majority criterion, is a voting system criterion that says that if a majority of voters ranks a certain group of candidates at the top of their ballot, then one of these candidates should win the election.
The Borda count electoral system can be combined with an instant-runoff procedure to create hybrid election methods that are called Nanson method and Baldwin method. Both methods are designed to satisfy the Condorcet criterion, and allow for incomplete ballots and equal rankings.
In single-winner voting system theory, the Condorcet loser criterion (CLC) is a measure for differentiating voting systems. It implies the majority loser criterion but does not imply the Condorcet winner criterion.
Anti-plurality voting describes an electoral system in which each voter votes against a single candidate, and the candidate with the fewest votes against wins. Anti-plurality voting is an example of a positional voting method.
Reversal symmetry is a voting system criterion which requires that if candidate A is the unique winner, and each voter's individual preferences are inverted, then A must not be elected. Methods that satisfy reversal symmetry include Borda count, ranked pairs, Kemeny–Young method, and Schulze method. Methods that fail include Bucklin voting, instant-runoff voting and Condorcet methods that fail the Condorcet loser criterion such as Minimax.
The Kemeny–Young method is an electoral system that uses ranked ballots and pairwise comparison counts to identify the most popular choices in an election. It is a Condorcet method because if there is a Condorcet winner, it will always be ranked as the most popular choice.
The later-no-harm criterion is a voting system criterion first formulated by Douglas Woodall. Woodall defined the criterion by saying that "[a]dding a later preference to a ballot should not harm any candidate already listed." For example, a ranked voting method in which a voter adding a 3rd preference could reduce the likelihood of their 1st preference being selected, fails later-no-harm.
The summability criterion is a voting system criterion, used to objectively compare electoral systems. The criterion states:
Instant-runoff voting (IRV), also known as plurality with elimination or plurality loser, is a ranked-choice voting system that modifies plurality by repeatedly eliminating the last-place winner until only one candidate is left. In the United Kingdom, it is generally called the alternative vote (AV). In the United States, IRV is often referred to as ranked-choice voting (RCV), by way of conflation with ranked voting systems in general.
Majority judgment (MJ) is a single-winner voting system proposed in 2010 by Michel Balinski and Rida Laraki. It is a kind of highest median rule, a cardinal voting system that elects the candidate with the highest median rating.
A unified primary is an electoral system for narrowing the field of candidates for a single-winner election, similar to a nonpartisan blanket primary, but using approval voting for the first round, advancing the top-two candidates, allowing voters to confirm the majority-supported candidate in the general election.
A major branch of social choice theory is devoted to the comparison of electoral systems, otherwise known as social choice functions. Viewed from the perspective of political science, electoral systems are rules for conducting elections and determining winners from the ballots cast. From the perspective of economics, mathematics, and philosophy, a social choice function is a mathematical function that determines how a society should make choices, given a collection of individual preferences.
Descending Solid Coalitions (DSC) is a ranked-choice voting system. It is designed to preserve the advantages of instant-runoff voting, while satisfying monotonicity. It was developed by voting theorist Douglas Woodall as an improvement on (and replacement for) the use of the alternative vote.