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Later-no-harm Criterion
Later-no-harm is a property of some Ranked voting, ranked-choice voting systems, first described by Douglas Woodall. In later-no-harm systems, increasing the rating or rank of a candidate ranked below the winner of an election cannot cause a higher-ranked candidate to lose. It is a common property in the plurality-rule family of voting systems. For example, say a group of voters ranks Alice 2nd and Bob 6th, and Alice wins the election. In the next election, Bob focuses on expanding his appeal with this group of voters, but does not manage to defeat Alice—Bob's rating increases from 6th-place to 3rd. Later-no-harm says that this increased support from Alice's voters should not allow Bob to win. Later-no-harm may be confused as implying center squeeze, since later-no-harm is a defining characteristic of Plurality voting, first-preference plurality (FPP) and Instant-runoff voting, instant-runoff voting (IRV), and descending solid coalitions (DSC), systems that have similar mechani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plurality Voting
Plurality voting refers to electoral systems in which the candidates in an electoral district who poll more than any other (that is, receive a plurality) are elected. Under single-winner plurality voting, and in systems based on single-member districts, plurality voting is called single member istrictplurality (SMP), which is widely known as " first-past-the-post". In SMP/FPTP the leading candidate, whether or not they have a majority of votes, is elected. There are several versions of plurality voting for multi-member district. The system that elects multiple winners at once with the plurality rule and where each voter casts as many X votes as the number of seats in a multi-seat district is referred to as plurality block voting. A semi-proportional system that elects multiple winners elected at once with the plurality rule and where each voter casts more than one vote but fewer than the number of seats to fill in a multi-seat district is known as limited voting. A semi-prop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plurality-rule Family
In social choice theory, the majority rule (MR) is a social choice rule which says that, when comparing two options (such as Bill (law), bills or Candidate, candidates), the option preferred by more than half of the voters (a ''majority'') should win. In political philosophy, the ''majority rule'' is one of two major competing notions of democracy. The most common alternative is given by the utilitarian rule (or other welfarist rules), which identify the spirit of liberal democracy with the equal consideration of interests.Ball, Terence and Antis Loizides"James Mill" The Stanford Encyclopedia of Philosophy (Winter 2020 Edition), Edward N. Zalta (ed.). Although the two rules can disagree in theory, political philosophers beginning with James Mill have argued the two can be reconciled in practice, with majority rule being a valid approximation to the utilitarian rule whenever voters share similarly-strong preferences. This position has found strong support in many Social choice the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Condorcet Method
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'' or ''Pairwise Majority Rule Winner'' (PMRW). The head-to-head elections need not be done separately; a voter's choice within any given pair can be determined from the ranking. Some elections may not yield a Condorcet winner because voter preferences may be cyclic—that is, it is possible that every candidate has an opponent that defeats them in a two-candidate contest. The possibility of such cyclic preferences is known as the Condorcet paradox. However, a smallest group of candidates that beat all candidates not in the group, known as the Smith set, always exists. The Smith set is guaranteed to have the Condorcet winner in it should one exist. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bucklin Voting
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. Voting process Bucklin rules varied, but here is a typical example: Voters are allowed rank preference ballots (first, second, third, etc.). First choice votes are first counted. If one candidate has a majority, that candidate wins. Otherwise the second choices are added to the first choices. Again, if a candidate with a majority vote is found, the winner is the candidate with the most votes accumulated. Lower rankings are added as needed. A majority is determined based on the number of valid ballots. Since, after the first round, there may be more votes cast than vot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Highest Median Voting Rules
The highest median voting rules are a class of graded voting rules where the candidate with the highest median rating is elected. The various highest median rules differ in their treatment of ties, i.e., the method of ranking the candidates with the same median rating. Proponents of highest median rules argue that they provide the most faithful reflection of the voters' opinion. They note that as with other cardinal voting rules, highest medians are not subject to Arrow's impossibility theorem. However, critics note that highest median rules violate participation and the Archimedean property; highest median rules can fail to elect a candidate almost-unanimously preferred over all other candidates. Example As in score voting, voters rate candidates along a common scale, e.g.: An elector can give the same appreciation to several different candidates. A candidate not evaluated automatically receives the mention "Bad". Then, for each candidate, we calculate what percentage o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Score Voting
Score voting, sometimes called range voting, is an electoral system for single-seat elections. Voters give each candidate a numerical score, and the candidate with the highest average score is elected. Score voting includes the well-known approval voting (used to calculate approval ratings), but also lets voters give partial (in-between) approval ratings to candidates. Usage Political use Historical A crude form of score voting was used in some elections in ancient Sparta, by measuring how loudly the crowd shouted for different candidates. This has a modern-day analog of using clapometers in some television shows and the judging processes of some athletic competitions. Beginning in the 13th century, the Republic of Venice elected the Doge of Venice using a multi-stage process with multiple rounds of score voting. This may have contributed to the Republic's longevity, being partly responsible for its status as the longest-lived democracy in world history. Score voting w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-round System
The two-round system (TRS or 2RS), sometimes called ballotage, top-two runoff, or two-round plurality, is a single-winner electoral system which aims to elect a member who has support of the majority of voters. The two-round system involves one or two rounds of choose-one voting, where the voter marks a single favorite candidate in each round. If no one has a majority of votes in the first round, the two candidates with the most votes in the first round move on to a second election (a second round of voting). The two-round system is in the family of plurality voting systems that also includes single-round plurality (FPP). Like instant-runoff (ranked-choice) voting and first past the post, it elects one winner. The two-round system first emerged in France and has since become the most common single-winner electoral system worldwide. Despite this, runoff-based rules like the two-round system and RCV have faced criticism from social choice theorists as a result of their suscep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monotonicity Criterion
Electoral system criteria In social choice, the negative response, perversity, or additional support paradox is a pathological behavior of some voting rules where a candidate loses as a result of having too much support (or wins because of increased opposition). In other words, increasing (decreasing) a candidate's ranking or rating causes that candidate to lose (win), respectively. Electoral systems that do not exhibit perversity are sometimes said to satisfy the monotonicity criterion.D R Woodall"Monotonicity and Single-Seat Election Rules" '' Voting matters'', Issue 6, 1996 Perversity is often described by social choice theorists as an exceptionally severe kind of electoral pathology, as such rules can have "backwards" responses to voters' opinions, where popularity causes defeat while unpopularity leads to a win. Similar rules treat the well-being of some voters as "less than worthless". These issues have led to constitutional prohibitions on such systems as violating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instant Runoff Voting
Instant-runoff voting (IRV; ranked-choice voting (RCV), preferential voting, alternative vote) is a single-winner ranked voting election system where one or more eliminations are used to simulate runoff elections. When no candidate has a majority of the votes in the first round of counting, each following round eliminates the candidate with the fewest first-preferences (among the remaining candidates) and transfers their votes if possible. This continues until one candidate accumulates a majority of the votes still in play. Instant-runoff voting falls under the plurality-based voting-rule family, in that under certain conditions the candidate with the least votes is eliminated, making use of secondary rankings as contingency votes. Thus it is related to the two-round runoff system and the exhaustive ballot. IRV could also be seen as a single-winner equivalent of single transferable voting. Unlike first-past-the-post voting, IRV is a sequential procedure. Unlike contin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bullet Voting
Bullet, single-shot, or plump voting is when a voter supports only a single candidate, typically to show strong support for a single favorite. Every voting method that does not satisfy either later-no-harm (most methods) or monotonicity (such as instant-runoff voting) will encourage bullet voting or truncation in some situations. In systems that fail later-no-harm, voters who feel strongly about their favorite candidate can use bullet voting to maximize the chances their favorite candidate will be elected, at the cost of reducing the chances that one of their later preferences will win. In non-participatory systems (such as instant-runoff), voters can sometimes strategically bullet-vote to hide their support for additional candidates; this strategy works because such systems can cause candidates to lose when they receive ''too'' ''much'' support from voters. Setups where voters may benefit from truncating their ballots are sometimes called a truncation paradox or Burr d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Truncation (voting)
Strategic or tactical voting is voting in consideration of possible ballots cast by other voters in order to maximize one's satisfaction with the election's results. Gibbard's theorem shows that no voting system has a single "always-best" strategy, i.e. one that always maximizes a voter's satisfaction with the result, regardless of other voters' ballots. This implies all voting systems can sometimes encourage voters to strategize. However, weaker guarantees can be shown under stronger conditions. Examples include one-dimensional preferences (where the median rule is strategyproof) and dichotomous preferences (where approval or score voting are strategyproof). With large electoral districts, party list methods tend to be difficult to manipulate in the absence of an electoral threshold. However, biased apportionment methods can create opportunities for strategic voting, as can small electoral districts (e.g. those used most often with the single transferable vote). Proportio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
