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Deliberation and the Wisdom of Crowds
No full textDocuments de travail du Centre d'Economie de la Sorbonne 2022.11 - ISSN : 1955-611XVersion originale Avril 2022, révisée en Décembre 2023, révisée en Juin 2024Does pre-voting group deliberation improve majority outcomes? To address this question, we develop a probabilistic model of opinion formation and deliberation. Two new jury theorems, one pre-deliberation and one post-deliberation, suggest that deliberation is beneficial. Successful deliberation mitigates three voting failures: (1) overcounting widespread evidence, (2) neglecting evidential inequality, and (3) neglecting evidential complementarity. Formal results and simulations confirm this. But we identify four systematic exceptions where deliberation reduces majority competence, always by increasing Failure 1. Our analysis recommends deliberation that is 'participatory', 'neutral', but not necessarily 'equal', i.e., that involves substantive sharing, privileges no evidences, but might privilege some persons
Why people should run after positive affective experiences instead of health benefits
No full textInternational audience• Promoting health benefits is necessary but insufficient to foster sustained engagement in physical activity (PA). • Our formal decision-making model explains why health benefits hold a weak subjective value. • In this model, expected health benefits are jointly discounted by effort-discounting, delay-discounting, and beliefs distortion. • In contrast, positive affective experiences toward PA can reduce the perception of effort, provide more immediate consequences, and strengthen beliefs about health benefits. • Because affective experiences have the potential to tip the balance in favor of PA over sedentary alternatives, they should be at the core of PA promotion
A Branch-and-Price algorithm for the electric autonomous Dial-A-Ride Problem
No full textInternational audienceThe Electric Autonomous Dial-A-Ride Problem (E-ADARP) consists in scheduling a fleet of electric autonomous vehicles to provide ride-sharing services for customers that specify their origins and destinations. The E-ADARP considers the following perspectives: (i) a weighted-sum objective that minimizes both total travel time and total excess user ride time; (ii) the employment of electric autonomous vehicles and a partial recharging policy. This paper presents the first labeling algorithm for a path-based formulation of the DARP/E-ADARP, where the main ingredient includes: (1) fragment-based representation of paths, (2) a novel approach that abstracts fragments to arcs while ensuring excess-user-ride-time optimality, (3) construction of a sparser new graph with the abstracted arcs, which is proven to preserve all feasible routes of the original graph, and (4) strong dominance rules and constant-time feasibility checks to compute the shortest paths efficiently. This labeling algorithm is then integrated into Branch-and-Price (B&P) algorithms to solve the E-ADARP. In the computational experiments, the B&P algorithm achieves optimality in 71 out of 84 instances. Remarkably, among these instances, 50 were solved optimally at the root node without branching. We identify 26 new best solutions, improve 30 previously reported lower bounds, and provide 17 new lower bounds for large-scale instances with up to 8 vehicles and 96 requests. In total 42 new best solutions are generated on previously solved and unsolved instances. In addition, we analyze the impact of incorporating the total excess user ride time within the objectives and allowing unlimited visits to recharging stations. The following managerial insights are provided: (1) solving a weighted-sum objective function can significantly enhance the service quality, while still maintaining operational costs at nearly optimal levels, (2) the relaxation on charging visits allows us to solve all instances feasibly and further reduces the average solution cost
Monitoring microplastics in the Seine River in the Greater Paris area
No full textInternational audienceThis data paper presents microplastic (MP) concentration and composition data from four campaigns in a one-year period in the Seine River within the Greater Paris area. Detailed data on MP occurrence, physical water parameters, hydrological conditions, and potential sewer point sources are presented. Initial analysis of the data set shows that MP concentrations were significant (median: 600 particles m −3 and 100 mg m −3 ) and MP fluxes showed variations across sampling sites and campaigns. Three polymer types (polypropylene - PP, polyethylene - PE, polystyrene - PS) account for 96% of the total number of MP. This dataset provides valuable insights for understanding river MP pollution under anthropogenic pressure
Team production on the battlefield: Evidence from NATO in Afghanistan
No full textManaging military operations across and between teams of partner nations remains a first-order challenge to security and development during conflict. NATO, under the umbrella of the International Security Assistance Force (ISAF), brought together troops from 28 countries to help enhance security provision in Afghanistan. ISAF units were given responsibility for specific operational units. The assignment of responsibilities to different national armed forces could lead to coordination problems. We explore whether the provision of security is affected by horizontal frictions (when different countries are responsible for different sides of borders) or vertical frictions (when different countries control different levels of the operational hierarchy). We find that both horizontal frictions and vertical frictions reduce military support activities, including aid projects. They are also associated with higher levels of insurgent violence. These findings indicate that misalignment between units within military organizations can undermine the effectiveness of security and development interventions during war, with broader implications for managing complex teams under risk
Structural evolutions of MX80 bentonite pellet/powder mixtures under wetting and suction-controlled oedometer loading
No full textInternational audienceThe compression behaviour of MX80 bentonite pellet/powder mixture was investigated by performing suction-controlled oedometer tests. The suction from 113 to 4.2 MPa was imposed by vapour equilibrium technique (VET), and zero suction by water circulation (WC). After instantaneously unloaded from various target vertical stresses, the structural observation was conducted by mercury intrusion porosimetry and micro-computed tomography. Results showed that during wetting, the intra-grain micro- and macro-pores increased due to the swelling of pellets and powder grains. During loading, the variation of intra-grain micro-pores was characterised by the loading effect, while that of intra-grain micro-pores was controlled by the suction and loading effects. The inter-grain pores, for the VET samples, were reduced by the swelling of pellets and powder grains during wetting on one hand, and by the movement of pellets and powder grains during loading on the other hand. For the WC samples, most inter-grain pores were closed during wetting, with a few pores in the top closed by further loading. The global compression of bentonite mixture samples during loading was mainly governed by the filling of inter-grain pores for the VET samples, but controlled by the compression of intra-grain pores for the WC samples
Plastic litter accumulation zones on the riverbanks of the Seine River (France): what about microplastics?
No full textInternational audienceRivers act as pathways for plastic litter but also constitute major accumulation zones. In the Seine estuary, several accumulation zones where macroplastics can have residence time up to decades are well known, which raise the question about the production of microplastics within these sites. To answer this question, 9 sites with different dynamics of accumulation and remobilization were studied by sampling mud (n = 13) in their intertidal zones and soil or sand (n = 15) in their supratidal zones. Samples were taken either in the macroplastics patches or around. Microplastic (> 25 µm) were analyzed by µFTIR imaging in transmission mode and with a 25 µm x 25 µm pixel resolution. Results demonstrate high contamination levels with concentrations ranging from 300 to 230 000 MP/kg of dry matter. Between 1 and 10 different polymers were identified according to samples. Polystyrene is the most concentrated polymer. Except for one site, microplastic concentrations are higher in soil samples than in mud samples (median values equal to 30 000 and 5 000 MP/kg, respectively). This tendency may result from a greater accumulation and a longer residence time of microplastic the supratidal zones than in the intertidal ones, but also from the degradation of macroplastics at the surface of these soils. In fact, whatever the sample types, microplastic tend to be more concentrated and coarser in the macroplastic patches than around. This trend is even more visible in the sites where macroplastic remobilization is the lowest
Does universalization ethics justify participation in large elections?
No full textWhat drives voters’ decisions to participate in large elections under costly voting, despite the rational expectation that this has no impact on the outcome? We propose a new model of ethical voters, by positing that they have Kantian or semi-Kantian preferences. With such preferences, voters evaluate their behavior in light of what the outcome would be, should a fraction of the other voters choose the same course of action. The “other voters” can be either the entire population (“non-partisan ethics”) or the individuals with same interest (“partisan ethics”). In a model with two candidates and a continuum of voters, we find that turnout is strictly positive as soon as the evaluation by the voters of the political outcome is not strictly of the “winner-take-all” kind. Moreover, the equilibrium turnout rates depend on the specifics of the election at hand, such as the relative stake of the election for the two supporter groups and the presence of core constituent groups
Alpha-maxmin as an aggregation of two selves
No full textThis paper offers a novel perspective on the α-maxmin model, taking its components as originating from distinct selves within the decision maker. Drawing from the notion of multiple selves prevalent in inter-temporal decision-making contexts, we present an aggregation approach where each self possesses its own preference relation. Contrary to existing interpretations, these selves are not merely a means to interpret the decision maker’s overall utility function but are considered as primitives. Through consistency requirements, we derive an α-maxmin representation as an outcome of a convex combination of the preferences of two distinct selves. We first explore a setting involving objective information and then move on to a fully subjective derivation