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Approval voting: Difference between revisions
Integrating the text I copied in from English Wikipedia
(Copied block of intro from w:Approval voting ( specifically, this version: https://en.wikipedia.org/w/index.php?title=Approval_voting&oldid=1036612916 ). I plan to do some more copyediting this evening (and not leave it like this).) |
(Integrating the text I copied in from English Wikipedia) |
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[[File:Approval ballot.svg|thumb|right|On an approval ballot, the voter can select any number of candidates.]]
'''Approval voting''' is a single-winner [[electoral system]] where each voter may select ("approve") any number of candidates. The winner is the
Approval voting can also be used in multiwinner elections. See "[[W:Multiwinner approval voting|multiwinner approval voting]]" on [[English Wikipedia]] to learn more about the multi-winner variant of approval voting.
[[Robert J. Weber]] coined the term "Approval Voting" in 1971.<ref>{{citation|title=Approval Voting|first1=Steven J.|last1=Brams|author1-link=Steven Brams|first2=Peter C.|last2=Fishburn|author2-link=Peter C. Fishburn|page=xv|publisher=Springer-Verlag|year=2007|isbn=978-0-387-49895-9|url=https://books.google.com/books?id=e7h7evxSclIC&pg=PR5}}</ref> It was more fully published in 1978 by political scientist [[Steven Brams]] and mathematician [[Peter Fishburn]].<ref>{{Cite journal | doi = 10.2307/1955105 |last1=Brams |first1=Steven |last2=Fishburn |first2=Peter | year = 1978 | title = Approval Voting | jstor = 1955105| journal = American Political Science Review | volume = 72 | issue = 3 | pages = 831–847 }}</ref>▼
Proposals to implement approval voting for municipal elections in the United States, were approved in referendums in Fargo, North Dakota, in 2018, and St. Louis, Missouri, in 2020. Fargo used approval voting in June 2020 to elect two at-large seats on its city council,<ref name="Ballotpedia Fargo">[https://ballotpedia.org/Fargo,_North_Dakota,_Measure_1,_Approval_Voting_Initiative_(November_2018) Fargo, North Dakota, Measure 1, Approval Voting Initiative (November 2018)], November 7, 2018 ''[[Ballotpedia]]''</ref><ref name="Fargo approves">[https://ivn.us/2018/11/06/one-americas-famous-towns-becomes-first-nation-adopt-approval-voting/ One of America’s Most Famous Towns Becomes First in the Nation to Adopt Approval Voting] {{Webarchive|url=https://web.archive.org/web/20181107185459/https://ivn.us/2018/11/06/one-americas-famous-towns-becomes-first-nation-adopt-approval-voting/|date=2018-11-07}}, accessed November 7, 2018</ref><ref name="Fargo votes">{{cite web |url=https://www.publicnewsservice.org/2020-06-10/civic-engagement/fargo-becomes-first-u-s-city-to-try-approval-voting/a70495-1 |title=Fargo Becomes First U.S. City to Try Approval Voting |last=Moen |first=Mike |date=June 10, 2020 |work=Public News Service |access-date=December 3, 2020 }}</ref><ref name="St. Louis approves">{{cite web|last=|first=|date=November 4, 2020|title=St. Louis Voters Approve Nonpartisan Elections|url=https://www.usnews.com/news/best-states/missouri/articles/2020-11-04/st-louis-voters-approve-nonpartisan-elections|url-status=live|archive-url=|archive-date=|access-date=December 3, 2020|work=US News and World Report}}</ref> and St. Louis used it to advance two candidates in March 2021
(<small>brief intro above copied from Wikipedia<ref>Introduction copied from Wikipedia's [[Approval voting]] article ([https://en.wikipedia.org/w/index.php?title=Approval_voting&oldid=967925338 oldid=967925338])</ref></small>)▼
▲[[Robert J. Weber]] coined the term "Approval Voting" in 1971.<ref>{{citation|title=Approval Voting|first1=Steven J.|last1=Brams|author1-link=Steven Brams|first2=Peter C.|last2=Fishburn|author2-link=Peter C. Fishburn|page=xv|publisher=Springer-Verlag|year=2007|isbn=978-0-387-49895-9|url=https://books.google.com/books?id=e7h7evxSclIC&pg=PR5}}</ref> It was more fully published in 1978 by political scientist [[Steven Brams]] and mathematician [[Peter Fishburn]].<ref>{{Cite journal | doi = 10.2307/1955105 |last1=Brams |first1=Steven |last2=Fishburn |first2=Peter | year = 1978 | title = Approval Voting | jstor = 1955105| journal = American Political Science Review | volume = 72 | issue = 3 | pages = 831–847 }}</ref>
▲(<small>brief intro above copied from Wikipedia<ref>Introduction copied from Wikipedia's [[Approval voting]] article ([https://en.wikipedia.org/w/index.php?title=Approval_voting&oldid=967925338 oldid=967925338] and [https://en.wikipedia.org/w/index.php?title=Approval_voting&oldid=1036612916 oldid=1036612916])</ref></small>)
▲Proposals to implement approval voting for municipal elections in the United States, were approved in referendums in Fargo, North Dakota, in 2018, and St. Louis, Missouri, in 2020. Fargo used approval voting in June 2020 to elect two at-large seats on its city council,<ref name="Ballotpedia Fargo">[https://ballotpedia.org/Fargo,_North_Dakota,_Measure_1,_Approval_Voting_Initiative_(November_2018) Fargo, North Dakota, Measure 1, Approval Voting Initiative (November 2018)], November 7, 2018 ''[[Ballotpedia]]''</ref><ref name="Fargo approves">[https://ivn.us/2018/11/06/one-americas-famous-towns-becomes-first-nation-adopt-approval-voting/ One of America’s Most Famous Towns Becomes First in the Nation to Adopt Approval Voting] {{Webarchive|url=https://web.archive.org/web/20181107185459/https://ivn.us/2018/11/06/one-americas-famous-towns-becomes-first-nation-adopt-approval-voting/|date=2018-11-07}}, accessed November 7, 2018</ref><ref name="Fargo votes">{{cite web |url=https://www.publicnewsservice.org/2020-06-10/civic-engagement/fargo-becomes-first-u-s-city-to-try-approval-voting/a70495-1 |title=Fargo Becomes First U.S. City to Try Approval Voting |last=Moen |first=Mike |date=June 10, 2020 |work=Public News Service |access-date=December 3, 2020 }}</ref><ref name="St. Louis approves">{{cite web|last=|first=|date=November 4, 2020|title=St. Louis Voters Approve Nonpartisan Elections|url=https://www.usnews.com/news/best-states/missouri/articles/2020-11-04/st-louis-voters-approve-nonpartisan-elections|url-status=live|archive-url=|archive-date=|access-date=December 3, 2020|work=US News and World Report}}</ref> and St. Louis used it to advance two candidates in March 2021 [[2021 St. Louis mayoral election|nonpartian primaries for]] mayor and aldermen.<ref>{{Cite web|last=Rakich|first=Nathaniel|date=2021-03-01|title=In St. Louis, Voters Will Get To Vote For As Many Candidates As They Want|url=https://fivethirtyeight.com/features/in-st-louis-voters-will-get-to-vote-for-as-many-candidates-as-they-want/|access-date=2021-03-04|website=FiveThirtyEight|language=en-US}}</ref><ref name=":0">{{Cite web|title=March 2, 2021 Non-Partisan Primary Municipal Election|url=https://www.stlouis-mo.gov/government/departments/board-election-commissioners/elections/election.cfm?customel_datapageid_524494=852866|url-status=live|access-date=2021-03-04|website=City of St. Louis Board of Election Commissioners|language=en}}</ref>
==Procedures==▼
▲==Procedures==
In this system, voters may vote for as many or as few candidates as the voter chooses. It is typically used for single-winner elections but can be extended to multiple winners. Approval voting is a limited form of [[range voting]], where the range that voters are allowed to express is extremely constrained: accept or not.
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*Memphis: 42 total votes
*Nashville: 68 total votes
*
*Knoxville: 32 total votes
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#Vote for every candidate you prefer to the leading candidate, and to also vote for the leading candidate if that candidate is preferred to the current second place candidate.
# For each candidate C, if the winner is more likely to come from the set of candidates that are worse than C than from the set of candidates that are better than C, then approve C, else don't.
In the above election, if Chattanooga is perceived as the strongest challenger to Nashville, voters from Nashville will only vote for Nashville, because it is the leading candidate and they prefer no alternative to it. Voters from Chattanooga and Knoxville will withdraw their support from Nashville, the leading candidate, because they do not support it over Chattanooga. The new results would be:
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If, however, Memphis were perceived as the strongest challenger, voters from Memphis would withdraw their votes from Nashville, whereas voters from Chattanooga and Knoxville would support Nashville over Memphis. The results would then be:
*Memphis: 42
* Nashville: 58
*Chattanooga: 32
*Knoxville: 32
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==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 who 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.
*Increasing options for voters, when compared with the common [[First-past-the-post election system|first-past-the-post system]], could increase voter turnout
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<br />
====Dichotomous preferences ====
The Approval voting winner is also always someone from the [[Smith set]] if voters' preferences truly are dichotomous (i.e. they don't have ranked preferences, but rather, honestly only support or oppose each candidate).
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Fully strategic Approval voting with perfectly informed voters generally elects the [[Condorcet winner]], and more generally, someone from the Smith set; this is because a plurality of voters have an incentive to set their [[Approval threshold|approval thresholds]] between the Smith candidate and the most-viable non-Smith candidate, resulting in at least the same approval-based margin as the Smith candidate has in their [[head-to-head matchup]] against the non-Smith candidate. A common argument for Approval>[[Condorcet methods]] is that when voters are honest, they get a utilitarian outcome, while if they are strategic, they at least get the CW. This is not as much the case with [[Score voting]] or [[STAR voting]], but it is not possible to figure out who the CW is from Approval ballots, since only limited [[pairwise counting]] information can be inferred.
====
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|-
|70
| 1st
| B
| ---
|'''20 (+10 Win)'''
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|-
|40
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|A
|
| ---
|
|'''30 (+10 Win)'''
|'''30 (+30 Win)'''
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|-
|30
|
|E
|10 (-40 Loss)
|20 (-10 Loss)
|
| ---
|'''20 (+20 Win)'''
|-
|10
|
|D
|10 (-40 Loss)
|0 (-30 Loss)
|10 (-30 Loss)
|0 (-10 Loss)
| ---
|}
This could also be done by treating each voter's Approval ballot as a ranked ballot where all approved candidates are equally ranked 1st and all other candidates are ranked last. This shows how Approval can be thought of as a Condorcet method where every candidate must be ranked either 1st or last.
====Strategically electing a pairwise-preferred candidate
Supposing rational voters (see [[Approval cutoff#Rationality restrictions]] for examples; chiefly, supposing voters who equally prefer two candidates approve both or neither of them), voters can "simulate" a [[head-to-head matchup]] in Approval voting in the sense that if, between two candidates, the voters who prefer the candidate who pairwise wins the matchup move their [[approval threshold]] between the two candidates, then they can guarantee that the candidate who pairwise loses the matchup is not elected (or if there was a pairwise tie between the two candidates, then they can guarantee a tie between the two candidates). This is because all voters who equally prefer the two candidates will not create an approval-based margin between the two candidates, and because there are more voters who prefer the pairwise winner of the matchup over the other candidate, the pairwise winner will guaranteeably have more approvals (specifically, they will have at least as high an approval-based margin as they do in their pairwise margin over the other candidate). Note however that they can '''not''' always make the pairwise winner of the matchup, or a candidate preferred more than or equally to the pairwise winner by any of the voters who prefer the pairwise winner over the pairwise loser, win. This is most easily seen in [[chicken dilemma]]-type situations; see [[Equilibrium#Notes]] for an example. However, this is true when the winner of the pairwise matchup [[majority-beat]]<nowiki/>s all other candidates.
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*[https://web.archive.org/web/20020429040757/http://www.fairvote.org/op_eds/science2001.htm Rebuttal to "The Science of Elections"], Center for Voting and Democracy.
===
<references />
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