Comparative Survey of Multiwinner Election Methods
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Critical Strategies Under Approval Voting: Who Gets Ruled in and Ruled Out
Critical Strategies Under Approval Voting: Who Gets Ruled In And Ruled Out Steven J. Brams Department of Politics New York University New York, NY 10003 USA [email protected] M. Remzi Sanver Department of Economics Istanbul Bilgi University 80310, Kustepe, Istanbul TURKEY [email protected] January 2005 2 Abstract We introduce the notion of a “critical strategy profile” under approval voting (AV), which facilitates the identification of all possible outcomes that can occur under AV. Included among AV outcomes are those given by scoring rules, single transferable vote, the majoritarian compromise, Condorcet systems, and others as well. Under each of these systems, a Condorcet winner may be upset through manipulation by individual voters or coalitions of voters, whereas AV ensures the election of a Condorcet winner as a strong Nash equilibrium wherein voters use sincere strategies. To be sure, AV may also elect Condorcet losers and other lesser candidates, sometimes in equilibrium. This multiplicity of (equilibrium) outcomes is the product of a social-choice framework that is more general than the standard preference-based one. From a normative perspective, we argue that voter judgments about candidate acceptability should take precedence over the usual social-choice criteria, such as electing a Condorcet or Borda winner. Keywords: approval voting; elections; Condorcet winner/loser; voting games; Nash equilibrium. Acknowledgments. We thank Eyal Baharad, Dan S. Felsenthal, Peter C. Fishburn, Shmuel Nitzan, Richard F. Potthoff, and Ismail Saglam for valuable suggestions. 3 1. Introduction Our thesis in this paper is that several outcomes of single-winner elections may be socially acceptable, depending on voters’ individual views on the acceptability of the candidates. -
Brake & Branscomb
Colorado Secretary of State 8/3/2021 Election Rulemaking These proposed edits to the SOS draft are contributed by Emily Brake (R) and Harvie Branscomb (D), and approved by Frank Atwood, Chair of the Approval Voting Party This document may be found on http://electionquality.com version 1.3 8/10/2021 15:50 Only portions of the recent draft rule text are included here with inline edits and comments highlighted as follows: Comments are highlighted in yellow. INSERTS ARE IN GREEN AND LARGE FONT deletions are in red and include strikeout Other indications of strikeout are from the original tabulation process 2.13.2 In accordance with section 1-2-605(7), C.R.S., no later than 90 days following a General Election, the county clerk in each county must SECRETARY OF STATE WILL PROPOSE cancelLATION OF the registrations of electors TO EACH COUNTY CLERK: [Comment: SOS taking responsibility from counties will lead to less verification and less resilience. The SOS office has not been subject to watcher access but will be as various steps of the conduct of election are taken over.] (a) Whose records have been marked “Inactive – returned mail”, “Inactive – undeliverable ballot”, or “Inactive – NCOA”; AND (b) Who have been mailed a confirmation card; and (c) Who have since THEREAFTER failed to vote in two consecutive general elections. New Rule 2.13.3, amendments to current Rule 2.13.3, repeal of 2.13.5, and necessary renumbering:VOTERS WHO REQUEST AN EMERGENCY BALLOT BE SENT TO THEM ELECTRONICALLY MUST BE DIRECTED BY THE COUNTY CLERK TO THE ONLINE BALLOT DELIVERY SYSTEM MAINTAINED BY THE SECRETARY OF STATE TO RECEIVE THEIR BALLOT ELECTRONICALLY. -
THE SINGLE-MEMBER PLURALITY and MIXED-MEMBER PROPORTIONAL ELECTORAL SYSTEMS : Different Concepts of an Election
THE SINGLE-MEMBER PLURALITY AND MIXED-MEMBER PROPORTIONAL ELECTORAL SYSTEMS : Different Concepts of an Election by James C. Anderson A thesis presented to the University of Waterloo in fulfillment of the thesis requirement for the degree of Master of Arts in Political Science Waterloo, Ontario, Canada, 2006 © James C. Anderson 2006 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Library and Bibliotheque et Archives Canada Archives Canada Published Heritage Direction du Branch Patrimoine de I'edition 395 Wellington Street 395, rue Wellington Ottawa ON K1A 0N4 Ottawa ON K1A 0N4 Canada Canada Your file Votre reference ISBN: 978-0-494-23700-7 Our file Notre reference ISBN: 978-0-494-23700-7 NOTICE: AVIS: The author has granted a non L'auteur a accorde une licence non exclusive exclusive license allowing Library permettant a la Bibliotheque et Archives and Archives Canada to reproduce,Canada de reproduire, publier, archiver, publish, archive, preserve, conserve,sauvegarder, conserver, transmettre au public communicate to the public by par telecommunication ou par I'lnternet, preter, telecommunication or on the Internet,distribuer et vendre des theses partout dans loan, distribute and sell theses le monde, a des fins commerciales ou autres, worldwide, for commercial or non sur support microforme, papier, electronique commercial purposes, in microform,et/ou autres formats. paper, electronic and/or any other formats. The author retains copyright L'auteur conserve la propriete du droit d'auteur ownership and moral rights in et des droits moraux qui protege cette these. this thesis. Neither the thesis Ni la these ni des extraits substantiels de nor substantial extracts from it celle-ci ne doivent etre imprimes ou autrement may be printed or otherwise reproduits sans son autorisation. -
Responsiveness, Capture and Efficient Policymaking
CENTRO DE INVESTIGACIÓN Y DOCENCIA ECONÓMICAS, A.C. ELECTIONS AND LOTTERIES: RESPONSIVENESS, CAPTURE AND EFFICIENT POLICYMAKING TESINA QUE PARA OBTENER EL GRADO DE MAESTRO EN CIENCIA POLÍTICA PRESENTA JORGE OLMOS CAMARILLO DIRECTOR DE LA TESINA: DR. CLAUDIO LÓPEZ-GUERRA CIUDAD DE MÉXICO SEPTIEMBRE, 2018 CONTENTS I. Introduction .............................................................................................................. 1 II. Literature Review ..................................................................................................... 6 1. Political Ambition .............................................................................................. 6 2. Electoral Systems and Policymaking ................................................................. 7 3. The Revival of Democracy by Lot ..................................................................... 8 III. Lottocracy in Theory .............................................................................................. 12 IV. Elections and Lotteries ........................................................................................... 14 1. Responsiveness ................................................................................................. 14 2. Legislative Capture ........................................................................................... 16 3. Efficiency.......................................................................................................... 18 V. A Formal Model of Legislator’s Incentives .......................................................... -
Are Condorcet and Minimax Voting Systems the Best?1
1 Are Condorcet and Minimax Voting Systems the Best?1 Richard B. Darlington Cornell University Abstract For decades, the minimax voting system was well known to experts on voting systems, but was not widely considered to be one of the best systems. But in recent years, two important experts, Nicolaus Tideman and Andrew Myers, have both recognized minimax as one of the best systems. I agree with that. This paper presents my own reasons for preferring minimax. The paper explicitly discusses about 20 systems. Comments invited. [email protected] Copyright Richard B. Darlington May be distributed free for non-commercial purposes Keywords Voting system Condorcet Minimax 1. Many thanks to Nicolaus Tideman, Andrew Myers, Sharon Weinberg, Eduardo Marchena, my wife Betsy Darlington, and my daughter Lois Darlington, all of whom contributed many valuable suggestions. 2 Table of Contents 1. Introduction and summary 3 2. The variety of voting systems 4 3. Some electoral criteria violated by minimax’s competitors 6 Monotonicity 7 Strategic voting 7 Completeness 7 Simplicity 8 Ease of voting 8 Resistance to vote-splitting and spoiling 8 Straddling 8 Condorcet consistency (CC) 8 4. Dismissing eight criteria violated by minimax 9 4.1 The absolute loser, Condorcet loser, and preference inversion criteria 9 4.2 Three anti-manipulation criteria 10 4.3 SCC/IIA 11 4.4 Multiple districts 12 5. Simulation studies on voting systems 13 5.1. Why our computer simulations use spatial models of voter behavior 13 5.2 Four computer simulations 15 5.2.1 Features and purposes of the studies 15 5.2.2 Further description of the studies 16 5.2.3 Results and discussion 18 6. -
MGF 1107 FINAL EXAM REVIEW CHAPTER 9 1. Amy (A), Betsy
MGF 1107 FINAL EXAM REVIEW CHAPTER 9 1. Amy (A), Betsy (B), Carla (C), Doris (D), and Emilia (E) are candidates for an open Student Government seat. There are 110 voters with the preference lists below. 36 24 20 18 8 4 A E D B C C B C E D E D C B C C B B D D B E D E E A A A A A Who wins the election if the method used is: a) plurality? b) plurality with runoff? c) sequential pairwise voting with agenda ABEDC? d) Hare system? e) Borda count? 2. What is the minimum number of votes needed for a majority if the number of votes cast is: a) 120? b) 141? 3. Consider the following preference lists: 1 1 1 A C B B A D D B C C D A If sequential pairwise voting and the agenda BACD is used, then D wins the election. Suppose the middle voter changes his mind and reverses his ranking of A and B. If the other two voters have unchanged preferences, B now wins using the same agenda BACD. This example shows that sequential pairwise voting fails to satisfy what desirable property of a voting system? 4. Consider the following preference lists held by 5 voters: 2 2 1 A B C C C B B A A First, note that if the plurality with runoff method is used, B wins. Next, note that C defeats both A and B in head-to-head matchups. This example shows that the plurality with runoff method fails to satisfy which desirable property of a voting system? 5. -
On the Distortion of Voting with Multiple Representative Candidates∗
The Thirty-Second AAAI Conference on Artificial Intelligence (AAAI-18) On the Distortion of Voting with Multiple Representative Candidates∗ Yu Cheng Shaddin Dughmi David Kempe Duke University University of Southern California University of Southern California Abstract voters and the chosen candidate in a suitable metric space (Anshelevich 2016; Anshelevich, Bhardwaj, and Postl 2015; We study positional voting rules when candidates and voters Anshelevich and Postl 2016; Goel, Krishnaswamy, and Mu- are embedded in a common metric space, and cardinal pref- erences are naturally given by distances in the metric space. nagala 2017). The underlying assumption is that the closer In a positional voting rule, each candidate receives a score a candidate is to a voter, the more similar their positions on from each ballot based on the ballot’s rank order; the candi- key questions are. Because proximity implies that the voter date with the highest total score wins the election. The cost would benefit from the candidate’s election, voters will rank of a candidate is his sum of distances to all voters, and the candidates by increasing distance, a model known as single- distortion of an election is the ratio between the cost of the peaked preferences (Black 1948; Downs 1957; Black 1958; elected candidate and the cost of the optimum candidate. We Moulin 1980; Merrill and Grofman 1999; Barbera,` Gul, consider the case when candidates are representative of the and Stacchetti 1993; Richards, Richards, and McKay 1998; population, in the sense that they are drawn i.i.d. from the Barbera` 2001). population of the voters, and analyze the expected distortion Even in the absence of strategic voting, voting systems of positional voting rules. -
Single-Winner Voting Method Comparison Chart
Single-winner Voting Method Comparison Chart This chart compares the most widely discussed voting methods for electing a single winner (and thus does not deal with multi-seat or proportional representation methods). There are countless possible evaluation criteria. The Criteria at the top of the list are those we believe are most important to U.S. voters. Plurality Two- Instant Approval4 Range5 Condorcet Borda (FPTP)1 Round Runoff methods6 Count7 Runoff2 (IRV)3 resistance to low9 medium high11 medium12 medium high14 low15 spoilers8 10 13 later-no-harm yes17 yes18 yes19 no20 no21 no22 no23 criterion16 resistance to low25 high26 high27 low28 low29 high30 low31 strategic voting24 majority-favorite yes33 yes34 yes35 no36 no37 yes38 no39 criterion32 mutual-majority no41 no42 yes43 no44 no45 yes/no 46 no47 criterion40 prospects for high49 high50 high51 medium52 low53 low54 low55 U.S. adoption48 Condorcet-loser no57 yes58 yes59 no60 no61 yes/no 62 yes63 criterion56 Condorcet- no65 no66 no67 no68 no69 yes70 no71 winner criterion64 independence of no73 no74 yes75 yes/no 76 yes/no 77 yes/no 78 no79 clones criterion72 81 82 83 84 85 86 87 monotonicity yes no no yes yes yes/no yes criterion80 prepared by FairVote: The Center for voting and Democracy (April 2009). References Austen-Smith, David, and Jeffrey Banks (1991). “Monotonicity in Electoral Systems”. American Political Science Review, Vol. 85, No. 2 (June): 531-537. Brewer, Albert P. (1993). “First- and Secon-Choice Votes in Alabama”. The Alabama Review, A Quarterly Review of Alabama History, Vol. ?? (April): ?? - ?? Burgin, Maggie (1931). The Direct Primary System in Alabama. -
A Canadian Model of Proportional Representation by Robert S. Ring A
Proportional-first-past-the-post: A Canadian model of Proportional Representation by Robert S. Ring A thesis submitted to the School of Graduate Studies in partial fulfilment of the requirements for the degree of Master of Arts Department of Political Science Memorial University St. John’s, Newfoundland and Labrador May 2014 ii Abstract For more than a decade a majority of Canadians have consistently supported the idea of proportional representation when asked, yet all attempts at electoral reform thus far have failed. Even though a majority of Canadians support proportional representation, a majority also report they are satisfied with the current electoral system (even indicating support for both in the same survey). The author seeks to reconcile these potentially conflicting desires by designing a uniquely Canadian electoral system that keeps the positive and familiar features of first-past-the- post while creating a proportional election result. The author touches on the theory of representative democracy and its relationship with proportional representation before delving into the mechanics of electoral systems. He surveys some of the major electoral system proposals and options for Canada before finally presenting his made-in-Canada solution that he believes stands a better chance at gaining approval from Canadians than past proposals. iii Acknowledgements First of foremost, I would like to express my sincerest gratitude to my brilliant supervisor, Dr. Amanda Bittner, whose continuous guidance, support, and advice over the past few years has been invaluable. I am especially grateful to you for encouraging me to pursue my Master’s and write about my electoral system idea. -
Approval Voting Under Dichotomous Preferences: a Catalogue of Characterizations
Draft – June 25, 2021 Approval Voting under Dichotomous Preferences: A Catalogue of Characterizations Florian Brandl Dominik Peters University of Bonn Harvard University [email protected] [email protected] Approval voting allows every voter to cast a ballot of approved alternatives and chooses the alternatives with the largest number of approvals. Due to its simplicity and superior theoretical properties it is a serious contender for use in real-world elections. We support this claim by giving eight characterizations of approval voting. All our results involve the reinforcement axiom, which requires choices to be consistent across different electorates. In addition, we consider strategyproofness, consistency with majority opinions, consistency under cloning alternatives, and invariance under removing inferior alternatives. We prove our results by reducing them to a single base theorem, for which we give a simple and intuitive proof. 1 Introduction Around the world, when electing a leader or a representative, plurality is by far the most common voting system: each voter casts a vote for a single candidate, and the candidate with the most votes is elected. In pioneering work, Brams and Fishburn (1983) proposed an alternative system: approval voting. Here, each voter may cast votes for an arbitrary number of candidates, and can thus choose whether to approve or disapprove of each candidate. The election is won by the candidate who is approved by the highest number of voters. Approval voting allows voters to be more expressive of their preferences, and it can avoid problems such as vote splitting, which are endemic to plurality voting. Together with its elegance and simplicity, this has made approval voting a favorite among voting theorists (Laslier, 2011), and has led to extensive research literature (Laslier and Sanver, 2010). -
Automated Verification for Functional and Relational Properties of Voting
Automated Verification for Functional and Relational Properties of Voting Rules Bernhard Beckert, Thorsten Bormer, Michael Kirsten, Till Neuber, and Mattias Ulbrich Abstract In this paper, we formalise classes of axiomatic properties for voting rules, discuss their characteristics, and show how symmetry properties can be exploited in the verification of other properties. Following that, we describe how automated verification methods such as software bounded model checking and deductive verification can be used to verify implementations of voting rules. We present a case study, where we use and compare different approaches to verify that plurality voting satisfies the majority and the anonymity property. 1 Introduction Axiomatic definitions of characteristic properties for voting rules are important both for understanding existing voting rules and for designing new ones. For the trustworthiness of elections, it is also important to analyse the algorithmic descriptions of voting rules and to prove that they have the desired properties, i.e., they satisfy the declarative description. There are two classes of voting rule properties, namely (a) functional (absolute) properties, such as the majority criterion, which refer to single voting results, and (b) relational properties, such as anonymity, which are defined by comparing two (or more) results. In this paper, we first formally define these two classes of properties and discuss their characteristics (Section 2). We then show how symmetry properties { which are a particular kind of relational properties { can be exploited to more efficiently verify voting rules w.r.t. other (functional) properties (Section 3). Proving properties of voting rules by hand is tedious and error-prone { in particular, if the rules and properties evolve during design and various versions have to be verified. -
Crowdsourcing Applications of Voting Theory Daniel Hughart
Crowdsourcing Applications of Voting Theory Daniel Hughart 5/17/2013 Most large scale marketing campaigns which involve consumer participation through voting makes use of plurality voting. In this work, it is questioned whether firms may have incentive to utilize alternative voting systems. Through an analysis of voting criteria, as well as a series of voting systems themselves, it is suggested that though there are no necessarily superior voting systems there are likely enough benefits to alternative systems to encourage their use over plurality voting. Contents Introduction .................................................................................................................................... 3 Assumptions ............................................................................................................................... 6 Voting Criteria .............................................................................................................................. 10 Condorcet ................................................................................................................................. 11 Smith ......................................................................................................................................... 14 Condorcet Loser ........................................................................................................................ 15 Majority ...................................................................................................................................