Comparing Election Methods Where Each Voter Ranks Only Few Candidates

Election rules are formal processes that aggregate voters preferences, typically to select a single candidate, called the winner. Most of the election rules studied in the literature require the voters to rank the candidates from the most to the least preferred one. This method of eliciting preferences is impractical when the number of candidates to be ranked is large. We ask how well certain election rules (focusing on positional scoring rules and the Minimax rule) can be approximated from partial preferences collected through one of the following procedures: (i) randomized-we ask each voter to rank a random subset of $\ell$ candidates, and (ii) deterministic-we ask each voter to provide a ranking of her $\ell$ most preferred candidates (the $\ell$-truncated ballot). We establish theoretical bounds on the approximation ratios and we complement our theoretical analysis with computer simulations. We find that mostly (apart from the cases when the preferences have no or very little structure) it is better to use the randomized approach. While we obtain fairly good approximation guarantees for the Borda rule already for $\ell = 2$, for approximating the Minimax rule one needs to ask each voter to compare a larger set of candidates in order to obtain good guarantees

Social Choice for Partial Preferences Using Imputation

Within the field of multiagent systems, the area of computational social choice considers the problems arising when decisions must be made collectively by a group of agents. Usually such systems collect a ranking of the alternatives from each member of the group in turn, and aggregate these individual rankings to arrive at a collective decision. However, when there are many alternatives to consider, individual agents may be unwilling, or unable, to rank all of them, leading to decisions that must be made on the basis of incomplete information. While earlier approaches attempt to work with the provided rankings by making assumptions about the nature of the missing information, this can lead to undesirable outcomes when the assumptions do not hold, and is ill-suited to certain problem domains. In this thesis, we propose a new approach that uses machine learning algorithms (both conventional and purpose-built) to generate plausible completions of each agent’s rankings on the basis of the partial rankings the agent provided (imputations), in a way that reflects the agents’ true preferences. We show that the combination of existing social choice functions with certain classes of imputation algorithms, which forms the core of our proposed solution, is equivalent to a form of social choice. Our system then undergoes an extensive empirical validation under 40 different test conditions, involving more than 50,000 group decision problems generated from real-world electoral data, and is found to outperform existing competitors significantly, leading to better group decisions overall. Detailed empirical findings are also used to characterize the behaviour of the system, and illustrate the circumstances in which it is most advantageous. A general testbed for comparing solutions using real-world and artificial data (Prefmine) is then described, in conjunction with results that justify its design decisions. We move on to propose a new machine learning algorithm intended specifically to learn and impute the preferences of agents, and validate its effectiveness. This Markov-Tree approach is demonstrated to be superior to imputation using conventional machine learning, and has a simple interpretation that characterizes the problems on which it will perform well. Later chapters contain an axiomatic validation of both of our new approaches, as well as techniques for mitigating their manipulability. The thesis concludes with a discussion of the applicability of its contributions, both for multiagent systems and for settings involving human elections. In all, we reveal an interesting connection between machine learning and computational social choice, and introduce a testbed which facilitates future research efforts on computational social choice for partial preferences, by allowing empirical comparisons between competing approaches to be conducted easily, accurately, and quickly. Perhaps most importantly, we offer an important and effective new direction for enabling group decision making when preferences are not completely specified, using imputation methods

Presidentialism, Parliamentarism, and Democracy Reconsidered

The purpose of this dissertation is to add to the understanding of democratic consolidation, and to address a debate within this topic: Is presidentialism harmful to democratic consolidation? I argue that presidentialism induces higher levels of political violence (attitudinally and behaviorally). Unlike parliamentary and semi-presidential systems, which offer mechanisms to alter the incumbent government through legislative responsibility, such as a vote of no confidence or a government reshuffle, when there exist mismatched policy expectations between the public and the government, or when the public dissatisfaction with the government is high, presidential systems do not have this mechanism to change the government composition and the president is empowered to govern until the next election. Even in the case that the public's discontent toward the president is high, there exist almost no mechanisms except for her own resignation and an impeachment to remove her from her office. However, a voluntary resignation and an impeachment are rarely occurred in the history, and thus, the expectation of the public regarding whether their grievances can be resolved and addressed is more difficult to be fulfilled in presidential democracies. Therefore, using and considering violence as a mean to address their political and social problems becomes a more viable option in presidential democracies. But by doing so, political stability will decrease and democratic consolidation will be hindered. I employ the World Value Survey and the Asian Barometer Survey to find support for this argument. To further extend this argument and to address the debate, I argue that democratic breakdown must be considered a two-step process. For a democracy to break down, the presence of a democratic crisis that presents a significant likelihood of overthrowing the current democratic regime is necessary. Specifically, I argue that presidentialism generates political instability through its institutions, which are associated with a greater likelihood of the emergence of a democratic crisis, but political instability does not further contribute from democratic crisis to democratic breakdown. Using data covering all democratic regimes from 1946 to 2008, I demonstrate that presidential democracies are more likely to encounter crises than either parliamentary or semi-presidential systems. However, once a crisis occurs, presidentialism does not lead to a higher likelihood of breakdown. Thus, presidentialism is associated with a higher likelihood of democratic breakdown, but only by affecting half of the process

Judicial Backlash or Just Backlash? Evidence from a National Experiment

The question about whether there is a distinctive public reaction when the Supreme Court decides constitutional issues — the question of judicial backlash — permeates our discussions of constitutional law, yet we have little to no empirical research about how people think about this issue. To answer this question, we conducted an experiment before the midterm congressional elections in the fall of 2010. We hypothesized that people respond to an institution based on whether the institution is seen as supporting or threatening their cultural worldview. Half of study subjects were assigned to a condition in which a constitutional right to gay marriage was protected and the other half were assigned to a condition in which a constitutional right to carry a concealed weapon was protected (with half of each of these subject populations being told the Court decided the issue and half being told that Congress did). Our results support the hypothesis that the cultural valence of the decision by the Court or Congress triggered the institutional choice of subjects. The Court does polarize underlying opinions on the constitutional issue and voting preferences more than Congress does. Our results suggest complications for efforts to decide constitutional issues in a manner appealing to all Americans. Our results also suggest that the Court and Congress might be able aggressively to decide constitutional issues because the public has no fixed sense of their respective institutional roles. We conclude by discussing what our results mean for interested communities outside of government, including social movements and constitutional theorists

Spatializing Partisan Gerrymandering Forensics: Local Measures and Spatial Specifications

abstract: Gerrymandering is a central problem for many representative democracies. Formally, gerrymandering is the manipulation of spatial boundaries to provide political advantage to a particular group (Warf, 2006). The term often refers to political district design, where the boundaries of political districts are “unnaturally” manipulated by redistricting officials to generate durable advantages for one group or party. Since free and fair elections are possibly the critical part of representative democracy, it is important for this cresting tide to have scientifically validated tools. This dissertation supports a current wave of reform by developing a general inferential technique to “localize” inferential bias measures, generating a new type of district-level score. The new method relies on the statistical intuition behind jackknife methods to construct relative local indicators. I find that existing statewide indicators of partisan bias can be localized using this technique, providing an estimate of how strongly a district impacts statewide partisan bias over an entire decade. When compared to measures of shape compactness (a common gerrymandering detection statistic), I find that weirdly-shaped districts have no consistent relationship with impact in many states during the 2000 and 2010 redistricting plan. To ensure that this work is valid, I examine existing seats-votes modeling strategies and develop a novel method for constructing seats-votes curves. I find that, while the empirical structure of electoral swing shows significant spatial dependence (even in the face of spatial heterogeneity), existing seats-votes specifications are more robust than anticipated to spatial dependence. Centrally, this dissertation contributes to the much larger social aim to resist electoral manipulation: that individuals & organizations suffer no undue burden on political access from partisan gerrymandering.Dissertation/ThesisDoctoral Dissertation Geography 201

Can citizens guess how other citizens voted based on demographic characteristics?

How well do citizens understand the associations between social groups and political divisions in their societies? Previous research has indicated systematic biases in how the demographic composition of party supporters are perceived, but this need not imply that citizens misperceive the likely voting behavior of specific individuals. We report results from two experiments where subjects were provided with randomly selected demographic profiles of respondents to the 2017 British Election Study (BES) and then asked to assess either (1) which party that individual was likely to have voted for in the 2017 UK election or (2) whether that individual was likely to have voted Leave or Remain in the 2016 UK referendum on EU membership. We find that, despite substantial overconfidence in individual responses, on average citizens’ guesses broadly reflect the actual distribution of groups supporting the parties and referendum positions

Policing Power: Essays on Coercion, Corruption, and the State

This dissertation is about how the state influences individuals’ behavior by giving certain citizens the legal and physical means to coerce other citizens. Using field experimentation, participatory observation, and time-series analysis of two large sets of micro-data on crime to study policing in West Africa and Melanesia, the findings challenge conventional wisdom about the relationship between coercion, corruption, and the state. Empowering women by sending police officers to assist them in disputes with men may not necessarily reduce gender-based coercion, because men can preserve their privileges by drawing on alternative authorities. Conferring police officers powers to coerce other people does not necessarily induce corrupt behavior, because conferral of power may cause them to care more about their reputation than the rents they can extract. Competitive elections may not reduce petty police corruption even if they make principals accountable; instead, elections may incentivize corruption by increasing agents’ uncertainty about how principals will act in the future. These findings contribute new insights to the theory of state-building, accountability, and bureaucratic politics

Fraudulent Elections, Political Protests, and Regime Transitions

This research studies protests after fraudulent elections in a collective action framework, examining the impact of the potential cost, benefit and likelihood of success of protest on the occurrence and intensity of protests. Quantitative analysis of fraudulent elections in about 100 countries from 1990 to 2004 shows that the odds of protest after fraudulent elections are greater when the level of state repression is moderate with a possible backlash effect of high repression, when the opposition is united, and when international monitors denounce election results. The analysis only partially supports the benefit of protest argument. Also, the research uses case studies from Eurasia (Armenia, Belarus, Georgia, and Russia) and mini-case studies from Africa and Latin America to study in more detail the effects of the factors identified in the quantitative analysis and to identify overlooked but important explanatory factors using a set of extensive interviews conducted in the United States and during fieldwork in Armenia, Georgia, and Russia with politicians, domestic and international election monitors, and country experts

Liberalization First, Democratization Later: The Linkage Between Income Inequality, Economic Development, and Democratization

This dissertation proposes a model of two-stage process of democratization. In the first stage, income inequality is associated with political liberalization, but this association is conditional on economic development. In the second stage, political liberalization is associated with democratization. By looking at 125 authoritarian regimes from 1960 to 2010, I find that in rich countries, high income inequality is associated with low political liberalization, which may stabilize autocratic regimes; while low income inequality is associated with high political liberalization. In poor countries, high income inequality is associated with political liberalization, while low inequality has no effect. In the second stage, I find that political liberalization, such as electoral component, liberal component, and participatory component of democracy are associated with democratization. These components of democracy may help citizens to develop prodemocracy attitude. This research attempts to extend the understanding of the relationship between income inequality, economic development, and democratization by including political liberalization

Towards a New Ontology of Polling Inaccuracy: The Benefits of Conceiving of Elections as Heterogenous Phenomena for the Study of Pre-election Polling Error

A puzzle exists at the heart of pre-election polling. Despite continual methodological improvement and repeated attempts to identify and correct issues laid bare by misprediction, average polling accuracy has not notably improved since the conclusion of the Second World War. In this thesis, I contend that this is the result of a poll-level focus within the study of polling error that is both incommensurate with its evolution over time and the nature of the elections that polls seek to predict. I hold that differences between elections stand as a plausible source of polling error and situate them within a novel four-level model of sources of polling error. By establishing the heterogenous nature of elections as phenomena and its expected impact on polling error, I propose a new election-level ontology through which the inaccuracy of polls can be understood. I test the empirical validity of this new ontology by using a novel multi-level model to analyse error across the most expansive polling dataset assembled to date, encompassing 11,832 in-campaign polls conducted in 497 elections across 83 countries, finding that membership within different elections meaningfully impacts polling error variation. With the empirical validity of my proposed ontology established, I engage in an exploratory analysis of its benefits, finding electoral characteristics to be useful in the prediction of polling error. Ultimately, I conclude that the adoption of a new, multi-level ontology of polling error centred on the importance of electoral heterogeneity not only offers a more comprehensive theoretical account of its sources than current understandings, but is also more specifically tailored to the reality of pre-election polling than existing alternatives. I also contend that it offers pronounced practical benefits, illuminating those circumstances in which polling error is likely to vary