Condorcet efficiency: A preference for indifference

The Condorcet winner in an election is the candidate who would be able to defeat all other candidates in a series of pairwise elections. The Condorcet efficiency of a voting procedure is the conditional probability that it will elect the Condorcet winner, given that a Condorcet winner exists. The study considers the Condorcet efficiency of weighted scoring rules (WSR's) on three candidates for large electorates when voter indifference between candidates is allowed. It is shown that increasing the proportion of voters who have partial indifference will increase the probability that a Condorcet winner exists, and will also increase the Condorcet efficiency of all WSR's. The same observation is observed when the proportion of voters with complete preferences on candidates is reduced. Borda Rule is shown to be the WSR with maximum Condorcet efficiency over a broad range of assumptions related to voter preferences. The result of forcing voters to completely rank all candidates, by randomly breaking ties on candidates that are viewed as indifferent, leads to a reduction in the probability that a Condorcet winner exists and to a reduction in the Condorcet efficiency of all WSR's. Received: 31 July 1999/Accepted: 11 February 2000     

A Note on “Discrete Sequential Search with Group Activities”

This note comments on a paper published by Wagner and Davis [Decision Sciences (2001), 32(4), 557–573]. These authors present an integer‐programming model for the single‐item discrete sequential search problem with group activities. Based on their experiments, they conjecture that the problem can be solved as a linear program. In this note, we provide a counterexample for which the optimal value of the linear program they propose is different from the optimal value of the integer‐programming model, hence contradicting their conjecture for the specific linear program that they specify. To the best of our knowledge, the conjecture settled in this note was still an open question.     

Body image,satisfaction with sexual life,self-esteem,and anxiodepressive symptoms: A comparative study between premenopausal,perimenopausal, and postmenopausal women

Menopause is an important life transition in women, and it is associated with significant physical and psychological changes. This study aimed at examining how the menopausal transition influences body image and satisfaction with sexual life. To this aim, body image dissatisfaction, sexual dissatisfaction, and self-esteem were compared in three groups of women with distinct menopausal status (premenopausal n = 142, perimenopausal n = 66, or postmenopausal n = 149), while controlling for depressive and anxiety symptoms and BMI. Using ANOVA between these three groups, we observed that dissatisfaction with body image was significantly higher in the perimenopausal sample compared with its premenopausal counterpart. In the postmenopausal sample, body image improved, as this group displayed body image scores close to the premenopausal level. In addition, sexual dissatisfaction was significantly increased in the perimenopausal and postmenopausal samples, which is compatible with the concept that higher body appreciation positively predicted sexual function. We conclude that body image dissatisfaction reaches a maximum during the perimenopausal phase, before returning to a level nearly identical between the premenopausal and the postmenopausal phases.     

The dynamic stochastic topic block model for dynamic networks with textual edges

Statistics and Computing - The present paper develops a probabilistic model to cluster the nodes of a dynamic graph, accounting for the content of textual edges as well as their frequency. Vertices...     

Women’s employment and the decline of home cooking: Evidence from France, 1985–2010

We here investigate the extent to which labour-market changes explain the decline in the time spent home cooking by married women in France between 1985 and 2010. Using time use data and Oaxaca-Blinder decompositions, we find that rising women’s employment and observed wages together account for about 60% of the fall in the time married women spent cooking. We then use a semi-parametric matching technique to construct an implicit wage rate, which better reflects the change in labour-market incentives that individuals face. The rise in women’s implicit wages explains no more than 20% of the decline in their cooking time, while the wage of their partner has no effect. Changing labour-market incentives are thus far from being the main driver of the decline in home-cooking. We also find evidence that home cooking continues to be structured by the gendered social norm of the “proper family meal”.     

Scoring Rules,Condorcet Efficiency and Social Homogeneity

Theory and Decision - In a three-candidate election, a scoring rule λ, λ∈[0,1], assigns 1,λ and 0 points (respectively) to each first, second and third place in the individual...     

Multiple change points detection and clustering in dynamic networks

The increasing amount of data stored in the form of dynamic interactions between actors necessitates the use of methodologies to automatically extract relevant information. The interactions can be represented by dynamic networks in which most existing methods look for clusters of vertices to summarize the data. In this paper, a new framework is proposed in order to cluster the vertices while detecting change points in the intensities of the interactions. These change points are key in the understanding of the temporal interactions. The model used involves non-homogeneous Poisson point processes with cluster-dependent piecewise constant intensity functions and common discontinuity points. A variational expectation maximization algorithm is derived for inference. We show that the pruned exact linear time method, originally developed for change points detection in univariate time series, can be considered for the maximization step. This allows the detection of both the number of change points and their location. Experiments on artificial and real datasets are carried out, and the proposed approach is compared with related methods.     

SOVEREIGN DEBT SUSTAINABILITY IN ADVANCED ECONOMIES

We develop a measure of maximum sustainable government debt for advanced economies. How much investors are willing to lend to a country's government depends on the country's expected primary surplus, the level and volatility of its rate of growth, and how much debt the government expects to be able to raise in the future for the purpose of servicing the debt it seeks to raise today. We provide a simple formula that computes a country's maximum sustainable debt (MSD) as a function of four easy‐to‐estimate parameters. We further compute a country's theoretical probability of default (PD) as a function of its debt‐to‐GDP ratio. We finally calibrate our measures for 23 OECD countries and test the relation between sovereign yield spreads and our theoretical PD at prevailing debt levels. We find it to be strongly statistically significant.     

Rules Trump Desires in Preschoolers’ Predictions of Group Behavior

The objective of this article is to investigate the way children weigh conventional rules against desires when considering how a group will behave. To do so, two experiments involving a prediction task in which desires were pitted against conventional rules were presented to three‐ to five‐year‐old children. In Experiment 1, four scenarios were established as classroom scenes in which either one protagonist or three protagonists had a desire that went against an explicit conventional rule. In the individual control condition, the choices linked to the rules were at chance whereas, in the group condition, the participants predicted that all the protagonists would end up following the rule. Given that both conditions in Experiment 1 implied four rule followers in the design, Experiment 2 staged not three but seven potential rule transgressors to see whether the desire of the majority might undermine the rule. Results showed no majority effect: participants expected protagonists to act counter to their desire and to follow the rule. Such results suggest that children as young as three‐year‐old favor rules over desires when they have to predict the behavior of a group, whether it be the majority or not. Possible implications of these intriguing findings are discussed.