Signalling, Incumbency Advantage, and Optimal Reelection Rules

Much literature on political behavior treats politicians as motivated by reelection, choosing actions to signal their types to voters. We identify two novel implications of models in which signalling incentives are important. First, because incumbents only care about clearing a reelection hurdle, signals will tend to cluster just above the threshold needed for reelection. This generates a skew distribution of signals leading to an incumbency advantage in the probability of election. Second, voters can exploit the signalling behavior of politicians by precommitting to a higher threshold for signals received. Raising the threshold discourages signalling effort by low quality politicians but encourages effort by high quality politicians, thus increasing the separation of signals and improving the selection function of an election. This precommitment has a simple institutional interpretation as a supermajority rule, requiring that incumbents exceed some fraction of votes greater than 50% to be reelected.Supermajority, incumbency advantage, signalling

Persuasion with correlation neglect: a full manipulation result

We consider an information design problem in which a sender tries to persuade a receiver that has "correlation neglect", i.e. fails to understand that signals might be correlated. We show that a sender with unlimited number of signals can fully manipulate the receiver. Specifically, the sender can induce the receiver to hold any state-dependent posterior she wishes to. If the sender only wishes to induce a state-independent posterior, she can use fully correlated signals, but generally she needs to design more involved correlation structures

Polarized extremes and the confused centre: campaign targeting of voters with correlation neglect

We model the effect of competing political campaigns on the opinion of voters who exhibit correlation neglect, i.e., fail to understand that different campaigns might be correlated. We show that political campaigners can manipulate voters' beliefs even when voters understand the informativeness of each campaign separately. The optimal coordination of campaigns involves negative correlation of good news and sometimes full positive correlation of bad news. We show that competition in targeted campaigns has the effect of changing the opinions of different groups in different ways; competition increases polarisation among extreme voters but at the same time increases the variance and the quality of moderates' voting decisions

The incumbency effects of signalling

Much literature on political behaviour treats politicians as motivated by re-election, choosing actions to signal their types to voters. We identify a novel implication of incumbent signalling. Because incumbents only care about clearing a re-election hurdle, signals will tend to cluster just above the threshold needed for re-election. This generates a skew distribution of signals leading to an incumbency advantage in the probability of election. We also solve for the optimal threshold when voters have the ability to commit

Signalling, incumbency advantage, and optimal reelection rules

Much literature on political behavior treats politicians as motivated by reelection, choosing actions to signal their types to voters. We identify two novel implications of models in which signalling incentives are important. First, because incumbents only care about clearing a reelection hurdle, signals will tend to cluster just above the threshold needed for reelection. This generates a skew distribution of signals leading to an incumbency advantage in the probability of election. Second, voters can exploit the signalling behavior of politicians by precommitting to a higher threshold for signals received. Raising the threshold discourages signalling effort by low quality politicians but encourages effort by high quality politicians, thus increasing the separation of signals and improving the selection function of an election. This precommitment has a simple institutional interpretation as a supermajority rule, requiring that incumbents exceed some fraction of votes greater than 50% to be reelected

Stable Partitions in Many Division Problems : The Proportional and the Sequential Dictator Solutions

We study how to partition a set of agents in a stable way when each coalition in the partition has to share a unit of a perfectly divisible good, and each agent has symmetric single-peaked preferences on the unit interval of his potential shares. A rule on the set of preference profiles consists of a partition function and a solution. Given a preference profile, a partition is selected and as many units of the good as the number of coalitions in the partition are allocated, where each unit is shared among all agents belonging to the same coalition according to the solution. A rule is stable at a preference profile if no agent strictly prefers to leave his coalition to join another coalition and all members of the receiving coalition want to admit him. We show that the proportional solution and all sequential dictator solutions admit stable partition functions. We also show that stability is a strong requirement that becomes easily incompatible with other desirable properties like efficiency, strategy-proofness, anonymity, and non-envyness

On Strategy-proofness and symmetric single-peakedness

We characterize the class of strategy-proof social choice functions on the domain of symmetric single-peaked preferences. This class is strictly larger than the set of generalized median voter schemes (the class of strategy-proof and tops-only social choice functions on the domain of single-peaked preferences characterized by Moulin (1980)) since, under the domain of symmetric single-peaked preferences, generalized median voter schemes can be disturbed by discontinuity points and remain strategy-proof on the smaller domain. Our result identifies the specific nature of these discontinuities which allow to design non-onto social choice functions to deal with feasibility constraints

Stable partitions in many division problems : the proportional and the sequential dictator solutions

We study how to partition a set of agents in a stable way when each coalition in the partition has to share a unit of a perfectly divisible good, and each agent has symmetric single-peaked preferences on the unit interval of his potential shares. A rule on the set of preference profiles consists of a partition function and a solution. Given a preference profile, a partition is selected and as many units of the good as the number of coalitions in the partition are allocated, where each unit is shared among all agents belonging to the same coalition according to the solution. A rule is stable at a preference profile if no agent strictly prefers to leave his coalition to join another coalition and all members of the receiving coalition want to admit him. We show that the proportional solution and all sequential dictator solutions admit stable partition functions. We also show that stability is a strong requirement that becomes easily incompatible with other desirable properties like e¢ ciency, strategy-proofness, anonymity, and non-envyness

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

On Strategy-proofness and symmetric single-peakedness

We characterize the class of strategy-proof social choice functions on the domain of symmetric single-peaked preferences. This class is strictly larger than the set of generalized median voter schemes (the class of strategy-proof and tops-only social choice functions on the domain of single-peaked preferences characterized by Moulin (1980)) since, under the domain of symmetric single-peaked preferences, generalized median voter schemes can be disturbed by discontinuity points and remain strategy-proof on the smaller domain. Our result identifies the specific nature of these discontinuities which allow to design non-onto social choice functions to deal with feasibility constraints