Single Transferable Vote Research Articles

Specyfika systemu pojedynczego głosu przechodniego (PR-STV) na przykładzie wyborów samorządowych w Irlandii i udziału w nich społeczności imigranckich

The aim of the article is a critical analysis of the electoral system of a single transferable vote on the example of local elections in Ireland and its evaluation from the point of view of key participants: voters, political parties and new players – immigrant candidates. The organization of elections, the vote counting methods and the rule of transfer of votes to seats as well as the influence of the electoral system on political parties strategies and voter behavior are presented in detail. In principle, the proportional system should be more friendly to independent candidates and small interest groups, but the case of immigrant candidates running in the elections in Ireland shows that in practice it is difficult for new players to achieve election success without the support of political parties. The analysis is based on a diverse sources, the review of academic literature and statistical data is complemented by the results of qualitative research – the in-depth interviews with Polish candidates running in the local elections in Ireland in the years 2009–2019.

Predicting winner and estimating margin of victory in elections using sampling

Predicting the winner of an election and estimating the margin of victory of that election are favorite problems both for news media pundits and computational social choice theorists. Since it is often infeasible to elicit the preferences of all the voters in a typical prediction scenario, a common algorithm used for predicting the winner and estimating the margin of victory is to run the election on a small sample of randomly chosen votes and predict accordingly. We analyze the performance of this algorithm for many commonly used voting rules.More formally, for predicting the winner of an election, we introduce the (ε,δ)-Winner Determination problem, where given an election E on n voters and m candidates in which the margin of victory is at least εn votes, the goal is to determine the winner with probability at least 1−δ where ε and δ are parameters with 0<ε,δ<1. The margin of victory of an election is the smallest number of votes that need to be modified in order to change the election winner. We show interesting lower and upper bounds on the number of samples needed to solve the (ε,δ)-Winner Determination problem for many common voting rules, including all scoring rules, approval, maximin, Copeland, Bucklin, plurality with runoff, and single transferable vote. Moreover, the lower and upper bounds match for many common voting rules up to constant factors.For estimating the margin of victory of an election, we introduce the (c,ε,δ)–Margin of Victory problem, where given an election E on n voters, the goal is to estimate the margin of victory M(E) of E within an additive error of cM(E)+εn with probability of error at most δ where ε,δ, and c are the parameters with 0<ε,δ<1 and c>0. We exhibit interesting bounds on the sample complexity of the (c,ε,δ)–Margin of Victory problem for many commonly used voting rules including all scoring rules, approval, Bucklin, maximin, and Copelandα. We observe that even for the voting rules for which computing the margin of victory is NP-hard, there may exist efficient sampling based algorithms for estimating the margin of victory, as observed in the cases of maximin and Copelandα voting rules.

The vote Package: Single Transferable Vote and Other Electoral Systems in R

The vote Package: Single Transferable Vote and Other Electoral Systems in R

Towards an Electoral Union? National Electoral Models, Strategies, and Effects at the 2019 EP Election

Since 1999, all member states have employed some form of proportional representation to elect representatives in the European Parliament. The introduction of Spitzenkandidaten and greater policy and campaigning coordination within Europarties sought to create a common European ground of party competition. However, the actual election of MEPs remains a national endeavor, determined by a national electoral framework. The electoral success of an Europarty in a given member state is shaped by the conditions set by the national electoral model for European elections. Different national models also give rise to different electoral strategies employed by parties wishing to maximize their number of MEPs. While electoral alliances might reflect cooperation of ideologically similar parties (such as list combinations in the Netherlands) or presidential majorities, like the coalition list of parties that support the French President, sometimes, especially in newer member states (e.g., Croatia), they might represent a strategic choice of ideologically divergent parties to work together in order to pass the threshold and win seats in the European Parliament. This paper seeks to compare different national playing grounds in which Europarties, i.e., their member parties compete, as well as electoral strategies that accompany such different frameworks. Apart from Ireland and Malta, which use the single transferable vote system, all other (current) member states use list proportional representation. However, the choice of a national electoral district or division in regional electoral constituencies can have a significant impact on electoral outcomes. Further, the employment of an electoral threshold and its interaction with district magnitude can create different electoral conditions. Finally, methods of seat allocation have an impact on prospects of smaller parties. A comparison of national electoral models will uncover different conditions and levels of (dis)proportionality that all weave together into the ultimate makeup of the European Parliament.

Ranked Choice Voting and Minority Representation

In this paper, we outline and demonstrate a data-driven methodology that voting rights advocates can use to compare the likely effectiveness of a single transferable vote system (STV) to single-member districts (SMD) for securing minority representation in local government. We incorporate both election data and demographics, and can apply variable assumptions on candidate availability and voter turnout. The core of our STV analysis uses four models of voter ranking behavior that take racial polarization into account; to assess districts, we use random district-generation algorithms developed at the MGGG Redistricting Lab. We demonstrate this method on four case studies: judicial elections in Terrebonne Parish, Louisiana; the county commission of Jones County, North Carolina; and the city councils of Cincinnati, Ohio and Pasadena, Texas. We find that STV provides proportional or slightly better representation for the relevant minority group in each case, while districts vary widely in their effectiveness depending on local circumstances.

The effects of electoral reform on party campaigns, voters and party systems at the local level: from single member plurality to the single transferable vote in Scotland

ABSTRACT Local electoral reform is important because local politics is a ‘missing link’ in understanding how electoral reform impacts upon political behaviour. This article discusses this question through examination of Scotland where the single transferable vote (STV) was introduced in 2007. This had consequences for party competition, how voters used their preferential ballot and local party system fragmentation. The article examines data from three rounds of STV local elections between 2007-2017, before comparing them with local elections under SMP. The first section applies debates regarding electoral reform and party systems to local elections. Sections two and three outline the electoral reforms implemented from 2007, and set out some expectations about voter and party behaviour. The fourth part examines local party candidate strategies, before the fifth section discusses voting behaviour under the STV system. The sixth section reflects on whether this has increased party system fragmentation at local level.

The ABCs of Electoral Reform: The Impact of Reading Levels on Knowledge, Interest and Opinion

AbstractHow should citizens be educated about complicated political issues like electoral reform? Are there basic principles that should be followed? This article tests one potential principle for government bodies, the media and educators to follow when conducting information campaigns: namely, lowering the reading level of information. Educators have long argued that texts can be confusing when written at a literacy level higher than the reader is able to digest. This article tests the impact of reading level on knowledge, interest and opinion on an electoral reform proposal. It employs an experimental design, conducted in person in fall 2018 with college students in Ontario, Canada. The experiment asked the students to read a text on a single transferable vote (STV) electoral system at one of three reading levels (or a control text) and then answer a series of questions gauging their knowledge, interest and opinion on the electoral reform proposal. The results provide an assessment of the impact of different levels of information on these factors and suggest concrete recommendations for election management bodies (EMBs) and other actors seeking to educate the public on complex political issues.

Recovering non-monotonicity problems of voting rules

A social choice rule (SCR) is monotonic if raising a single alternative in voters’ preferences while leaving the rankings otherwise unchanged is never detrimental to the prospects for winning of the raised alternative. Monotonicity is rather weak but well-known to discriminate against scoring elimination rules, such as plurality with a run off and single transferable vote. We define the minimal monotonic extension of an SCR as its unique monotonic supercorrespondence that is minimal with respect to set inclusion. After showing the existence of the concept, we characterize, for every non-monotonic SCR, the alternatives that its minimal monotonic extension must contain. As minimal monotonic extensions can entail coarse SCRs, we address the possibility of refining them without violating monotonicity provided that this refinement does not diverge from the original SCR more than the divergence prescribed by the minimal monotonic extension itself. We call these refinements monotonic adjustments and identify conditions over SCRs that ensure unique monotonic adjustments that are minimal with respect to set inclusion. As an application of our general findings, we consider plurality with a runoff, characterize its minimal monotonic extension as well as its (unique) minimal monotonic adjustment. Interestingly, this adjustment is not coarser than plurality with a runoff itself, hence we suggest it as a monotonic substitute to plurality with a runoff.

The transfers game: A comparative analysis of the mechanical effect of lower preference votes in STV systems

Debates about electoral reform revolve around giving voters more choice. Consequently, reformers often favor adopting the single transferable vote, a candidate-based system that allows voters to rank order candidates. Nonetheless, studies about whether lower preferences (transfers) influence STV election outcomes remain scant. To address this gap, our comparative multivariate approach tests transfers’ impact on election results in Ireland, Malta, Northern Ireland, and Scotland. We find that, on average, transfers are pivotal in the election of about one in 10 elected candidates. Hence, their impact is the exception rather than the norm. We show that when lower preferences are decisive at the candidate level, they benefit smaller and moderate parties and non-incumbents and, in Malta and Ireland, female candidates. Our results have implications for understanding the extent to which multiple preferences influence election outcomes and for debates on electoral reform.

Did That Lost Ballot Box Cost Me a Seat? Computing Manipulations of STV Elections

Mistakes made by humans, or machines, commonly arise when managing ballots cast in an election. In the 2013 Australian Federal Election, for example, 1,370 West Australian Senate ballots were lost, eventually leading to a costly re-run of the election. Other mistakes include ballots that are misrecorded by electronic voting systems, voters that cast invalid ballots, or vote multiple times at different polling locations. We present a method for assessing whether such problems could have made a difference to the outcome of a Single Transferable Vote (STV) election – a complex system of preferential voting for multi-seat elections. It is used widely in Australia, in Ireland, and in a range of local government elections in the United Kingdom and United States.

Impact of the Electoral System on Political Stability in Ethnically Divided Societies in Serbia and Bulgaria

The article focuses on the influence of the proportional electoral system with closed party lists in ethnically divided societies on the emergence of radical ethnic parties and on ethnic voting. The subject of the study is the political, electoral and party systems of Serbia and Bulgaria between 1991 and 2020. The following factors are considered: preservation of political stability, presence of radical ethnic parties within the party systems of the two states, and ethnic voting as a mode of conduct for voters, as well as the way to evade the phenomenon undertaking an institutional reform of the electoral system. The impact of a proportional system with closed party lists on ethnic voting and the formation of radical ethnic parties in Serbia and Bulgaria is analyzed, which is relevant in the Balkans as a whole. As a result of the study, the authors propose a shift from a proportional system with closed party lists to a single transferable vote system as a way of countering the rise of radical ethnic parties and of overcoming the destabilization of Balkan political systems.

Toward Computing the Margin of Victory in Single Transferable Vote Elections

The single transferable vote (STV) is a system of preferential voting for multiseat elections. Each ballot cast by a voter is a (potentially partial) ranking over a set of candidates. No techniques currently exist for computing the margin of victory (MOV) in STV elections. The MOV is the smallest number of ballot manipulations (changes, additions, and deletions) required to bring about a change in the set of elected candidates. Knowing the MOV gives insight into how much time and money should be spent on auditing the election, and whether uncovered mistakes (such as ballot box losses) throw the election result into doubt—requiring a costly repeat election—or can be safely ignored. We present algorithms for computing lower and upper bounds on the MOV in STV elections. In small instances, these algorithms are able to compute exact margins.

The Transferable Vote: A Hundred Years of Anglican Experience

I am grateful to the Society for the opportunity to mark the centenary of the Enabling Act and the beginning of the Church Assembly with some reflection on an often ignored but highly valuable feature of that inauguration: the Single Transferable Vote or STV. I tried on one respected registrar recently an illustration of what the task must be like for those who do not welcome it. Was it, I suggested, like a blind person doing a jigsaw where the pieces were all shaped differently from each other – in other words, where the blind person could ensure that it was put together accurately, but on the other hand never saw the picture? The response was that that picture reflected accurately how it had in fact felt to that registrar. That might suggest that this lecture should be explaining and commending STV as general good practice, but in the event the process and virtues of STV have here to be largely taken for granted. I offer here one short commendation of STV.

The expanding approvals rule: improving proportional representation and monotonicity

Proportional representation (PR) is often discussed in voting settings as a major desideratum. For the past century or so, it is common both in practice and in the academic literature to look towards the single transferable vote (STV) rule as the solution for achieving PR. Some of the most prominent electoral reform movements around the globe are pushing for the adoption of STV. It has been termed a major open problem to design a voting rule that satisfies the same PR properties as STV and better monotonicity properties. In this paper, we first present a taxonomy of proportional representation axioms for general weak order preferences, some of which generalise and strengthen previously introduced concepts. We then present a rule called the expanding approvals rule (EAR) that satisfies properties stronger than the central PR axiom satisfied by STV, can handle indifferences in a convenient and computationally efficient manner, and also satisfies better candidate monotonicity properties. In view of this, our proposed rule seems to be a compelling solution for achieving proportional representation in voting settings.

Ensemble feature selection using election methods and ranker clustering

Feature selection (FS) has become a significant part of the data processing pipeline. Recently, ensemble FS has emerged as a new methodology that promises to improve FS robustness and performance. In this paper, we propose several ensemble FS methods built on voting aggregation schemes such as plurality vote, single transferable vote, Borda count, and novel weighted Borda count. Additionally, we present the new concept of clustering FS methods prior to building ensembles using a mean-shift clustering algorithm. The proposed methods are examined using three accuracy measures: the ability to correctly identify relevant features, FS stability, and influence on classification. The ensembles and clustered ensembles based on a weighted Borda count show very balanced performance, achieving quality results in all investigated measures and outperforming the other methods examined.

Understanding Legislative Speech in the Turkish Parliament: Reconsidering the Electoral Connection under Proportional Representation

AbstractWe aim to address two weaknesses of the growing literature on legislative debate and legislative behaviour. First, most studies on legislative speech focus on the role of party unity and individual dissent on speech-making behaviour and largely ignore the role of legislators’ own calculations regarding their electoral vulnerability. Secondly, research on legislative behaviour that studies mechanisms other than legislative speech usually explores the role of electoral incentives where there is Single Member District (SMD) or open list system, and largely neglects closed list proportional representation systems with multi-member districts. We suggest that, similar to SMD and single transferable vote systems, the electoral vulnerability of individual legislators provides incentives to nurture a personal reputation and signals their efforts to their constituents and party leadership. Using a novel dataset of parliamentary speeches in the Turkish Parliament (2007–2011), we demonstrate that legislators who are electorally more vulnerable participate more in legislative debate, and are more likely to deliver constituency-related speeches.

Approximating optimal social choice under metric preferences

We consider voting under metric preferences: both voters and alternatives are associated with points in a metric space, and each voter prefers alternatives that are closer to her to ones that are further away. In this setting, it is often desirable to select an alternative that minimizes the sum of distances to the voters, i.e., the utilitarian social cost, or other similar measures of social cost. However, common voting rules operate on voters' preference rankings and therefore may be unable to identify an optimal alternative. A relevant measure of the quality of a voting rule is then its distortion, defined as the worst-case ratio between the performance of an alternative selected by the rule and that of an optimal alternative. Thus, distortion measures how good a voting rule is at approximating an alternative with minimum social cost, while using only ordinal preference information. The underlying costs can be arbitrary, implicit, and unknown; our only assumption is that they form a metric space. The goal of our paper is to quantify the distortion of well-known voting rules. We first establish a lower bound on the distortion of any deterministic voting rule. We then show that the distortion of positional scoring rules cannot be bounded by a constant, and for several popular rules in this family distortion is linear in the number of alternatives. On the other hand, for Copeland and similar rules the distortion is bounded by a factor of 5. These results hold both for the sum of voters' cost and the median voter cost. For Single Transferable Vote (STV), we obtain an upper bound of O(ln⁡m) with respect to the sum of voters' costs, where m is the number of alternatives, as well as a lower bound of Ω(ln⁡m); thus, STV is a reasonable, though not a perfect rule from this perspective. Our results for median voter cost extend to more general objective functions.

Evidence of a winning-cohesion tradeoff under multi-winner ranked-choice voting

New interest in "multi-winner ranked-choice voting" raises old questions about effects on party cohesion. Earlier scholars thought this single transferable vote (STV) rule was net-problematic for parties. This paper consults the roll-call and electoral records in Cincinnati (1929-57) and Worcester, Mass. (1949-60), two of three American STV implementations that produced conventional wisdom. First, I show how party cohesion could be high or low. Then I show how low-cohesion terms followed elections in which candidates campaigned for themselves over their parties. Finally, I show that parties endorsed such candidates when they needed the votes to expand their seat shares. In sum, the data suggest a strategic environment in which majority-seeking parties reach beyond their traditional bases – potentially at the expense of legislative cohesion. Whether that is good or bad depends on the value we give to cohesion.

Preferential Voting: Definition and Classification

There is no single definition for ‘preferential voting’ or ‘preference voting’ since the terms are used for a number of different election systems and groups of such systems. They can be synonymous with the single-transferable vote, the alternative vote, open-list proportional representation, or the group of all ranking methods. This article offers an overview of the various definitions and classifications of preferential voting and other terms used in the literature to describe it. It proposes a common understanding of preferential voting. I suggest that preferentiality ought to be one of the characteristics by which electoral systems are evaluated. All election systems are preferential, though to varying degrees. I offer a classification of numerous electoral schemes according to their preferentiality.

President election in Indian constitutional arrangement-a perusal

Article 54 of the Indian constitution is related to the election of the President of India. The President is elected indirectly by the members of an electorol college consisting of the elected members of both houses of Parliament and the elected members of the State Assemblies. The method of his election is based on proportional representation by means of single transferable vote system.