Split Cycle: A New Condorcet Consistent Voting Method Independent of Clones and Immune to Spoilers

We propose a Condorcet consistent voting method that we call Split Cycle. Split Cycle belongs to the small family of known voting methods that significantly narrow the choice of winners in the presence of majority cycles while also satisfying independence of clones. In this family, only Split Cycle satisfies a new criterion we call immunity to spoilers, which concerns adding candidates to elections, as well as the known criteria of positive involvement and negative involvement, which concern adding voters to elections. Thus, in contrast to other clone-independent methods, Split Cycle mitigates both "spoiler effects" and "strong no show paradoxes."Comment: 71 pages, 15 figures. Added a new explanation of Split Cycle in Section 1, updated the caption to Figure 2, the discussion in Section 3.3, and Remark 4.11, and strengthened Proposition 6.20 to Theorem 6.20 to cover single-voter resolvability in addition to asymptotic resolvability. Thanks to Nicolaus Tideman for helpful discussio

Split Cycle: A New Condorcet Consistent Voting Method Independent of Clones and Immune to Spoilers

We introduce a new Condorcet consistent voting method, called Split Cycle. Split Cycle belongs to the small family of known voting methods satisfying independence of clones and the Pareto principle. Unlike other methods in this family, Split Cycle satisfies a new criterion we call immunity to spoilers, which concerns adding candidates to elections, as well as the known criteria of positive involvement and negative involvement, which concern adding voters to elections. Thus, relative to other clone-independent Paretian methods, Split Cycle mitigates “spoiler effects” and “strong no show paradoxes.

How Hard Is It to Control an Election by Breaking Ties?

We study the computational complexity of controlling the result of an election by breaking ties strategically. This problem is equivalent to the problem of deciding the winner of an election under parallel universes tie-breaking. When the chair of the election is only asked to break ties to choose between one of the co-winners, the problem is trivially easy. However, in multi-round elections, we prove that it can be NP-hard for the chair to compute how to break ties to ensure a given result. Additionally, we show that the form of the tie-breaking function can increase the opportunities for control. Indeed, we prove that it can be NP-hard to control an election by breaking ties even with a two-stage voting rule.Comment: Revised and expanded version including longer proofs and additional result

Within-subject Intra- and Inter-method consistency of two experimental risk attitude elicitation

We compare the consistency of choices in two methods to used elicit risk preferences on an aggregate as well as on an individual level. We asked subjects to choose twice from a list of nine decision between two lotteries, as introduced by Holt and Laury (2002, 2005) alternating with nine decisions using the budget approach introduced by Andreoni and Harbaugh (2009). We find that while on an aggregate (subject pool) level the results are (roughly) consistent, on an individual (within-subject) level, behavior is far from consistent. Within each method as well as across methods we observe low correlations. This again questions the reliability of experimental risk elicitation measures and the ability to use results from such methods to control for the risk aversion of subjects when explaining effects in other experimental games.risk preferences, laboratory experiment, elicitation methods, subject heterogeneity

Risky Punishment and Reward in the Prisoner’s Dilemma

We conduct a prisoner’s dilemma experiment with a punishment/reward stage, where punishments and rewards are risky. This is compared with a risk free treatment. We find that subjects do not change their behavior in the face of risky outcomes. Additionally, we measure risk attitude and the emotions of subjects. While we find a strong influence of emotions, individual risk aversion has no effect on the decision to punish or reward. This is good news for lab experiments who abstract from risky outcomes. From the perspective of social preferences, our results provide evidence for risk neutral inclusion of other player’s payoffs in the decisionmaker’s utility function.Prisoner’s dilemma, risk, punishment, reward, emotions, experiment

The Cowl - v.82 -n.13 - Jan 18, 2018

The Cowl - student newspaper of Providence College. Volume 82, Number 13 - January 18, 2018. 24 pages

Obvious Independence of Clones

The Independence of Clones (IoC) criterion for social choice functions (voting rules) measures a function's robustness to strategic nomination. However, prior literature has established empirically that individuals cannot always recognize whether or not a mechanism is strategy-proof and may still submit costly, distortionary misreports even in strategy-proof settings. The intersection of these issues motivates the search for mechanisms which are Obviously Independent of Clones (OIoC): where strategic nomination or strategic exiting of clones obviously have no effect on the outcome of the election. We examine three IoC ranked-choice voting mechanisms and the pre-existing proofs that they are independent of clones: Single Transferable Vote (STV), Ranked Pairs, and the Schulze method. We construct a formal definition of a voting system being Obviously Independent of Clones based on a reduction to a clocked election by considering a bounded agent. Finally, we show that STV and Ranked Pairs are OIoC, whereas we prove an impossibility result for the Schulze method showing that this voting system is not OIoC