Voto aprobatorio
Na Galipedia, a wikipedia en galego.
O voto aprobatorio é un sistema de votación usado en eleccións, onde cada votante pode votar por tantos candidatos como desexe. É normalmente usado en elección nas que só pode haber un gañador. Pode ser usado en eleccións de gañador múltiple tamén, porén, nesta versión ten propiedades matemáticas moi diferentes, como embaixo se indica. O voto aprobatorio é unha forma primitiva de voto valorativo, onde as opcións do votante son extremadamente poucas: aceptar ou rexeitar. O voto aprobatorio evita a paradoxa presentada polo Teorema de imposibilidade de Arrow xa que non é un sistema de orde preferencial.
O método foi descrito nun ensaio de 1968 do astrónomo Guy Ottewll e publicado en 1977 baixo o nome de "The Arithmetic of Voting"[1]. O termo "voto aprobatorio" foi acuñado por Robert J. Weber en 1976, mais foi totalmente desenvolvido en 1977 e publicado en 1978 polo politólogo Steven Brams e o matemático Peter Fishburn. Historicamente, algo semellante ó voto aprobatorio foi utilizado durante o século XIII na República de Venecia e nas eleccións parlamentarias da Inglaterra do século XIX. Ademais, as Nacións Unidas usan un proceso semellante para elixir ó seu Secretario Xeral. Aínda que proposto en países como os Estados Unidos, actualmente non é usado en ningunhas eleccións públicas.
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[editar] Procedemento
Cada votante pode votar por tódalas opcións que queira, como máximo unha vez por opción. Isto ñe equivalente a dicir que cada votante pode "aprobar" ou "rexeitar" cada opción votando ou non por ela, e tamén é equivalente a dicir que é votar +1 ou 0 nun sistema de votación por rango. A opción con máis votos após o reconto gaña.
[editar] Exemplo
Imaxinemos que a poboación de Galiza vota a localización da súa capital. Para este exemplo, supoñamos que a poboación de Galiza está concentrada en catro cidades, sitas en todo o país, e que todo o electorado, que quere que a capital se estableza o máis preto posíbel da súa cidade, vive nestas catro.
Os candidatos para a capital son:
- Vigo, a cidade máis grande de Galiza, pero lonxe doutras cidades, cun 42% dos votos.
- A Coruña cun 26% dos votos.
- Santiago de Compostela cun 17% dos votos.
- Lugo cun 15% dos votos.
As preferencias do electorado dividiríanse así:
| 42% dos votos (preto de Vigo) |
26% dos votos (preto d'A Coruña) |
15% dos votos (preto de Lugo) |
17% dos votos (preto de Santiago de Compostela) |
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Supoñendo que os votantes votaron polas súas dous cidades favoritas e que Galiza ten 100 votantes, o resultado sería o seguinte:
- Vigo: 42 votos totais, só os da propia cidade.
- A Coruña: 58 votos totais, os da propia cidade mais os de Santiago de Compostela e Lugo.
- Lugo: 15 votos totais, só os da propia cidade.
- Santiago de Compostela: 85 votos totais, procedentes de tódalas urbes agás Lugo.
Santiago de Compostela seguiría a se-la capital de Galiza por voto aprobatorio.
[editar] Potencial para o voto táctico
O voto aprobatorio pasa o criterio da monotonicidade, no que a elección dun candidato nunca reduce as posibilidades de gañar dese candidato. Sen dúbida, nunca hai un motivo para o voto táctico polo candidato X sen votar por por tódolos candidatos que o votante prefira por riba do candidato de X. Tampouco é necesario votar por un candidato que lle guste menos ó votante que o candidato X para que X sexa elixido. Así, após que o votante decida a súa preferencia, só necesita decidir a cantos candidatos votará: en caso de n candidatos, vota a os seus k candidatos favoritos, onde 0 < k < n, sendo k decidido previamente (k = 0 ou k = n é inutil). Se o votante pensa que os dosu candidatos mais votados serán aqueles que estan nas posicións p e q, que na súa lista de preferencias están situados p > q, debe elixir k entre p e q, por exemplo, votando por p e non por q.
Como o voto aprobatorio non ofrece un método de expresar cal é o candidato máis desexado entre tódolos votados, senón un feixe deles, anímase ós votantes a que analicen as preferencias dos votantes da súa comunidade e a usar esa información para decidir a qué candidato votar. Esta característica do voto aprobatorio fai que sexa difícil para os teóricos predicir como se desenvolverá a votación.
Unha posíbel táctica é que o votante unicamente vote polo seu candidato preferido, o que fará máis difícil que outros cadidatos gañen. Se tódolos cahados a urnas usan esta táctica, a votación vólvese un escrutinio uninominal maioritario, onde o candidato coa maioría de votos de primeira preferencia gaña.
Outra táctica é votar por tódolos candidatos o votante prefire ó candidato que vai en cabeza, ou tamén votar polo candidato en cabeza se é preferido o que está en segunda posición. Cando tódolos chamados a urnas usan esta táctica, hai moitas posibilidades de que sexa elixido un gañador Condorcet. O voto aprobatorio non cumple os criterios de Condorcet, é incluso posíbel que un perdedor Condocet sexa elixido.
Teoricamente, a táctica óptima é votar por aqueles candidatos ós qu se prefiren en troques do que se espera que saia elixido na votación (a media ponderada da utilidade dos candidatos, tomando como peso as súas posibilidades de vitoria).
Nas eleccións de exemplo, se A Coruña é o rival máis forte de Santiago de Compostela, os votantes de Santiago só votarán pola súa cidade, xa que é a que leva vantaxe e prefiren que non haxa alternativa. Os votantes d'A Coruña e de Lugo retirarán o seu apoio a Santiago, o candidato máis forte, porque non apoian á Coruña. Os novos resultados serían:
- Vigo: 42 votos
- A Coruña: 47 votos
- Lugo: 15 votos
- Santiago de Compostela: 54 votos
Porén, se Vigo fora visto como o rival máis forte, os votates de Vigo deixarían de apoiar a Santiago, mentres que os votantes de A Coruña e Lugo apoiarían a Santiago por encima de Vigo. Os resultados serían:
- Vigo: 42 votos
- A Coruña: 58 votos
- Lugo: 15 votos
- Santiago de Compostela: 43 votos
[editar] Effect on elections
The effect of this system as an electoral reform measure is not without critics. Instant-runoff voting advocates like the Center for Voting and Democracy argue that approval voting would lead to the election of "lowest common denominator" candidates disliked by few, and liked by few, but this could also be seen as an inherent strength against demagoguery in favor of a discreet popularity. A study by approval advocates Steven Brams and Dudley R. Herschbach published in Science in 2001 [2] argued that approval voting was "fairer" than preference voting on a number of criteria. They claimed that a close analysis shows that the hesitation to support a lesser evil candidate to the same degree as one supports one's first choice actually outweighs the extra votes that such second choices get.
One study [3] showed that approval voting would not have chosen the same two winners as plurality voting (Chirac and Le Pen) in France's presidential election of 2002 (first round) - it instead would have chosen Chirac and Jospin. This seems a more reasonable result since Le Pen was a radical who lost to Chirac by an enormous margin in the second round.
While approval voting in single-winner elections is immune to cloning, its misuse as a multi-member method with teaming of candidates can produce ties, called the Burr dilemma. "Problems of multicandidate races in U.S. presidential elections motivated the modern invention and advocacy of approval voting; but it has not previously been recognized that the first four presidential elections (1788–1800) were conducted using a variant of approval voting. That experiment ended disastrously in 1800 with the infamous Electoral College tie between Jefferson and Burr. The tie,..., resulted less from miscalculation than from a strategic tension built into approval voting, which forces two leaders appealing to the same voters to play a game of Chicken."[4]
[editar] Other issues and comparisons
Advocates of approval voting often note that a single simple ballot can serve for single, multiple, or negative choices. It requires the voter to think carefully about whom or what they really accept, rather than trusting a system of tallying or compromising by formal ranking or counting. Compromises happen but they are explicit, and chosen by the voter, not by the ballot counting. Some features of approval voting include:
- Unlike Condorcet method, instant-runoff voting, and other methods that require ranking candidates, approval voting does not require significant changes in ballot design, voting procedures or equipment, and it is easier for voters to use and understand. This reduces problems with mismarked ballots, disputed results and recounts.
- It provides less incentive for negative campaigning than many other systems, through the same incentive as instant runoff voting, Condorcet method, and Borda count.
- It allows voters to express tolerances but not preferences. Some political scientists consider this a major advantage, especially where acceptable choices are more important than popular choices.
- Each voter may vote as many times as wished, at most once per candidate. This is equivalent to saying that each voter may approve or disapprove each candidate by voting or not voting for them, and it is also equivalent to voting +1 or 0 in a range voting system.
- It is easily reversed as disapproval voting where a choice is disavowed, as is already required in other measures in politics (e.g. representative recall).
- In contentious elections with a super-majority of voters who prefer their favorite candidate vastly over all others, approval voting tends to revert to plurality voting. Some voters will support only their single favored candidate when they perceive the other candidates to be poor compromises.
- Approval voting fails the majority criterion, because more than one person can win a majority of approval. (This requires that a larger majority also approve of the winner.)
[editar] Multiple winners
Approval voting can be extended to multiple winner elections. The naive way to do so is as block approval voting, a simple variant on block voting where each voter can select an unlimited number of candidates and the candidates with the most approval votes win. This does not provide proportional representation and is subject to the Burr dilemma, among other problems. It has also been extended as proportional approval voting which seeks to maximise the overall satisfaction with the final result using approval voting. That first system has been called minisum to distinguish it from minimax, a system which uses approval ballots and aims to elect the slate of candidates that differs from the least-satisfied voter's ballot as little as possible.
[editar] Approval polling
Approval voting can also be used to voting or polling questions which allow a variable number of winners.
A clear example is the question of candidate inclusion for debates. An approval poll would be better to ask: "Which candidates do you want to see in the debate?" rather than the usual polling question: "Who would you vote for if the election was today?"
In such a poll, a fixed threshold for inclusion could be made. For example, a debate could include all candidates above 15% approval support. Special rules would be needed to guarantee at least 2 candidates passing, possibly simply including all of candidates.
The advantage of approval polling is that voter have no fear that "overvoting" will hurt their higher choices. Undecided voters will tend to want to hear from more candidates early in the campaign, and will tend to reduce their preferences as voting day approaches.
[editar] Relation to effectiveness of choices
Operations research has shown that the effectiveness of a policy and thereby a leader who sets several policies will be sigmoidally related to the level of approval associated with that policy or leader.Modelo:Fact There is an acceptance level below which effectiveness is very low and above which it is very high. More than one candidate may be in the effective region, or all candidates may be in the ineffective region. Approval voting attempts to ensure that the most-approved candidate is selected, maximizing the chance that the resulting policies will be effective.
[editar] Ballot types
Approval ballots can be of at least four semi-distinct forms. The simplest form is a blank ballot where the names of supported candidates is written in by hand. A more structured ballot will list all the candidates and allow a mark or word to be made by each supported candidate. A more explicit structured ballot can list the candidates and give two choices by each. (Candidate list ballots can include spaces for write-in candidates as well.)
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All four ballots are interchangeable. The more structured ballots may aid voters in offering clear votes so they explicitly know all their choices. The Yes/No format can help to detect an "undervote" when a candidate is left unmarked and allow the voter a second chance to confirm the ballot markings are correct.
[editar] Vexa tamén
Modelo:Portal
- Borda count
- Bucklin voting
- First Past the Post electoral system (also called Plurality or Relative Majority)
- Condorcet method
- Schulze method
- Instant-runoff voting
- Majority Choice Approval
- Range voting
- Voting system - many other ways of voting
[editar] Referencias
- ↑ http://www.universalworkshop.com/pages/ArithmeticOfVoting.htm
- ↑ Brams and Herschbach Modelo:Cite journal
- ↑ Results of experimental vote in France, 2002 (PDF, French)
- ↑ http://www.journalofpolitics.org/files/69_1/Nagel.pdf The Burr Dilemma in Approval Voting
[editar] Ligazóns externas
- Citizens for Approval Voting
- Americans for Approval Voting
- Approval Voting Free Association Wiki
- Approval Voting: A Better Way to Select a Winner Article by Steven J. Brams.
- Approval Voting on Dichotomous Preferences Article by Marc Vorsatz.
- Scoring Rules on Dichotomous Preferences Article by Marc Vorsatz.
- Approval Voting: An Experiment during the French 2002 Presidential Election Article by Jean-François Laslier and Karine Vander Straeten.
- The Arithmetic of Voting article by Guy Ottewell
- Critical Strategies Under Approval Voting: Who Gets Ruled In And Ruled Out Article by Steven J. Brams and M. Remzi Sanver.
- Going from Theory to Practice:The Mixed Success of Approval Voting Article by Steven J. Brams and Peter C. Fishburn.
- Strategic approval voting in a large electorate Article by Jean-François Laslier.
- Spatial approval voting Article by Jean-François Laslier, published in Political Analysis (2006).
- Approval Voting with Endogenous Candidates An article by Arnaud Dellis and Mandor P. Oak.
- Generalized Spectral Analysis for Large Sets of Approval Voting Data Article by David Thomas Uminsky.
- Approval Voting and Parochialism Article by Jonathan Baron, Nicole Altman and Stephan Kroll.
