Publications

Résumé It can be assumed that higher SARS-CoV-2 infection risk is associated with higher COVID-19 vaccination intentions, although evidence is scarce. In this large and representative survey of 6007 adults aged 18–64 years and residing in France, 8.1% (95% CI, 7.5–8.8) reported a prior SARS-CoV-2 infection in December 2020, with regional variations according to an East–West gradient (p < 0.0001). In participants without prior SARS-CoV-2 infection, COVID-19 vaccine hesitancy was substantial, including 41.3% (95% CI, 39.8–42.8) outright refusal of COVID-19 vaccination. Taking into account five characteristics of the first approved vaccines (efficacy, duration of immunity, safety, country of the vaccine manufacturer, and place of administration) as well as the initial setting of the mass vaccination campaign in France, COVID-19 vaccine acceptance would reach 43.6% (95% CI, 43.0–44.1) at best among working-age adults without prior SARS-CoV-2 infection. COVID-19 vaccine acceptance was primarily driven by vaccine characteristics, sociodemographic and attitudinal factors. Considering the region of residency as a proxy of the likelihood of getting infected, our study findings do not support the assumption that SARS-CoV-2 infection risk is associated with COVID-19 vaccine acceptance.
Mots clés SARS-CoV-2, COVID-19, Mass vaccination, Anti-vaccination behavior, Vaccine hesitancy, Survey experiment, Discrete choice experiment, France
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Résumé Sub-Saharan Africa's hepatitis B virus (HBV) burden is primarily due to infection in infancy. However, data on chronic HBV infection prevalence and associated risk factors in children born post-HBV vaccination introduction are scarce. We estimated hepatitis B surface antigen (HBsAg) prevalence and risk factors in Senegalese children born during the HBV vaccination era. In 2018-2019, a community-based cross-sectional survey was conducted in Senegal among children born between 2004 and 2015 (ie after the three-dose HBV vaccine series was introduced (2004) but before the birth dose's introduction (2016)). HBsAg-positive children were identified using dried blood spots. A standardized questionnaire collected socioeconomic information. Data were age-sex weighted and calibrated to be representative of children living in the study area. Risk factors associated with HBsAg positivity were identified using negative binomial regression. Among 1,327 children, 17 were HBsAg-positive (prevalence = 1.23% (95% confidence interval [CI] 0.61-1.85)). Older age (adjusted incidence-rate ratio [aIRR] 1.31 per one-year increase, 95% CI 1.10-1.57), home vs healthcare facility delivery (aIRR 3.55, 95% CI 1.39-9.02), stitches (lifetime) (aIRR 4.79; 95% CI 1.84-12.39), tattoos (aIRR 8.97, 95% CI 1.01-79.11) and having an HBsAg-positive sibling with the same mother (aIRR 3.05, 95% CI 1.09-8.57) were all independently associated with HBsAg positivity. The low HBsAg prevalence highlights the success of the Senegalese HBV vaccination program. To further reduce HBV acquisition in children, high-risk groups, including pregnant women and siblings of HBsAg-positive individuals, must be screened. Vital HBV infection prevention measures include promoting delivery in healthcare facilities, and increasing awareness of prevention and control procedures.
Mots clés Child, Hepatitis B, Prevalence, Risk factors, Senegal
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Résumé This paper documents the determinants of real oil price in the global market based on an empirical model embedding transitory and permanent shocks. We find evidence of significant differences in the propagation mechanisms of transitory versus permanent disturbances, pointing to the importance of disentangling their distinct effects. Permanent supply shocks are found to be very influential in driving oil price fluctuations.
Mots clés Bayesian estimationKalman lteringNarrative analysisOil marketVector autoregressions
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Résumé Cette étude a pour objectif d’évaluer différents modes de financement de la couverture santé universelle au Sénégal. La méthode utilisée, la micro-simulation, permet d’examiner l’impact de différents scenarii sur les consommations des ménages ainsi que sur les dépenses publiques. Les résultats montrent que la généralisation d’une assurance-maladie à l’ensemble de la population, associée à une réduction des coûts directs des soins, augmenterait les consommations de soins des Sénégalais, améliorant donc leur accès aux services de santé. Néanmoins, une telle généralisation serait coûteuse pour les finances publiques. Pour limiter les coûts supportés par le gouvernement, l’augmentation du taux d’imposition sur la consommation et de la prime de contribution à l’assurance-maladie serait utile et permettrait de ramener les finances publiques à l’équilibre.
Mots clés Sahel, Coûts directs des soins, Finances publiques, Micro-simulation, Couverture sante universelle
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Résumé Knightian uncertainty represents a situation in which it is no longer possible to form expectations about future events. We propose a method to directly measure Knightian uncertainty. Our approach relies on firm-level data and measures the share of firms that do not formalize expectations about their future demand. We construct the Knightian Uncertainty Indicator for Switzerland and show that the indicator is able to identify times of high uncertainty. We evaluate the indicator by comparing it to established uncertainty measures. We find that a one standard deviation innovation of the Knightian Uncertainty Indicator leads to a negative and persistent reduction of investment.
Mots clés Business survey, Measurement, Uncertainty, Knight
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Résumé Many countries are reallocating tasks and powers to more central levels of government. To identify centralization’s welfare effects, I use a difference-in-differences design that relies on time and cross-cantonal variation in the implementation of centralization reforms in Switzerland. I find that centralization provokes significant decreases in residents’ life satisfaction. I identify one mechanism driving the effect, namely the procedural disutility that individuals experience from having less influence over the formulation of political decisions. This effect is largest among individuals with higher expected benefits from being involved in the political decision process, with detrimental effects on local political participation.
Mots clés Political participation, Procedural utility, Life satisfaction, Centralization
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Résumé Comment mesurer le plus finement possible l'accélération ou la décélération d'une épidémie ?
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Résumé Does giving taxpayers a voice over the destination of tax revenues lead to more honest income declarations? Previous experiments have shown that giving participants the opportunity to select the organization that receives their tax funds tends to increase tax compliance. The aim of this paper is to assess whether this increase in compliance is induced by the sole fact of giving subjects a choice—a “direct democracy effect”. To that aim, we ask participants to a tax evasion game to choose, in a collective or individual choice setting, between two very similar organizations which provide the same social (ecological) benefits. We elicit compliance for both organizations before the choice is made so as to control for the counter-factual compliance decision. We find that democracy does not increase compliance, and even observe a slight negative effect—in particular for women. Our results confirm the existence of a commitment effect of democracy, leading to favor more the selected organization when it was actively chosen. The commitment effect of democracy is however not enough to overcome the decrease in the level of compliance. Thanks to response times data, we show that prior choice on similar options as compared to a purely random selection weakens the preference for honesty. One important field application of our results is that democracy in tax spending must offer real choices to tax payers to improve compliance.
Mots clés Commitment, Direct democracy effect, Voting, Tax evasion game
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Résumé La part de l'aide humanitaire croît dans l'aide totale. Or les acteurs impliqués restent peu étudiés. Cet article documente la fragmentation de l'aide à un double niveau : celui des donneurs et celui des acteurs de terrains. Le jeu de délégation entre les deux peut réduire les effets négatifs de la fragmentation de l'aide. À partir de trois études de cas, le lien entre fragmentation, délégation et efficacité de l'aide humanitaire est illustré et les coûts et bénéfices potentiels
Mots clés Delegation, Fragmentation, Implementing agency, Donor, Humanitarian aid, Delegation, Intermédiaires, Donneurs, Fragmentation, Aide humanitaire
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Résumé This paper proposes two dominance criteria for evaluating education systems described as joint distributions of the pupils’ cognitive skill achievements and family backgrounds. The first criterion is the smallest transitive ranking of education systems compatible with three elementary principles. The first principle requires the favorable recording of any improvement in the cognitive skill of a child with a given family background . The second principle demands that any child’s cognitive skill be all the more favourably appraised as the child is coming from an unfavourable background. The third principle states that when two different skills and family backgrounds are allocated between two children, it is preferable that the high skill be given to the low background child than the other way around. Our second criterion adds to the three principles the elitist requirement that a mean-preserving spread in the skills of two children with the same background be recorded favorably. We apply our criteria to the ranking of education systems of 43 countries, where we measure cognitive skills by PISA score in mathematics and famly background by the largest of the two parents’International Socio Economic Index. Our criteria conclusively compare about 19% of all the possible pairs of countries.
Mots clés Maths scores, Dominance, International comparisons, Opportunities, Family background, Inequality, Education
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Résumé This study examines a specific class of common-pool resources whereby rivalry is not characterized by competition for the resource stock. Artesian aquifers are a typical example of such resources since the stock never depletes, even when part of the resource is extracted. We first propose a dynamic model to account for the relevant features of such aquifers such as the water pressure and well yield and characterize the corresponding dynamics. We then compare the social optimum with the private exploitation of an open-access aquifer. The comparison of these two equilibria highlights the existence of a new source of inefficiency. In the long run, this so-called pressure externality results in an additional number of wells for the same water consumption, thereby raising costs. Finally, we characterize a specific stock-dependent tax to neutralize the pressure externality.
Mots clés Dynamic optimization, Public regulation, Optimal management, Externality, Common-pool resource
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Résumé Online surveys of health professionals have become increasingly popular during the COVID-19 crisis because of their ease, speed of implementation, and low cost. This article leverages an online survey of general practitioners’ (GPs’) attitudes toward the soon-to-be-available COVID-19 vaccines, implemented in October–November 2020 (before the COVID-19 vaccines were authorized in France), to study the evolution of the distribution of their demographic and professional characteristics and opinions about these vaccines, as the survey fieldwork progressed, as reminders were sent out to encourage them to participate. Focusing on the analysis of the potential determinants of COVID-19 vaccine acceptance, we also tested if factors related to survey participation biased the association estimates. Our results show that online surveys of health professionals may be subject to significant selection bias that can have a significant impact on estimates of the prevalence of some of these professionals’ behavioral, opinion, or attitude variables. Our results also highlight the effectiveness of reminder strategies in reaching hard-to-reach professionals and reducing these biases. Finally, they indicate that weighting for nonparticipation remains indispensable and that methods exist for testing (and correcting) selection biases.
Mots clés Heckman method, Weighting, COVID-19, Practices, Attitudes, Selection bias, Online surveys, Health care professionals
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Résumé Akin to other developing countries, Algeria has witnessed an increasing role of the private health sector in the past two decades. Our study sheds light on the public–private overlap and the phenomenon of physician dual practice in the provision of health care services using the particular case of cesarean deliveries in Algeria. Existing studies have reported that, compared to the public sector, delivering in a private health facility increases the risk of enduring a cesarean section. While confirming this result for the case of Algeria, our study also reveals the existence of public–private differentials in the effect of medical variables on the probability of cesarean delivery. After controlling for selection in both sectors, we show that cesarean deliveries in the private sector tend to be less medically justified compared with those taking place in the public sector, thus, potentially leading to maternal and neonatal health problems. As elsewhere, the contribution of the private health sector to the unmet need for health care in Algeria hinges on an appropriate legal framework that better coordinates the activities of the two sectors and reinforces their complementarity.
Mots clés Cesarean delivery, Algeria, Physician dual practice, Public–private differentials
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Résumé In the US, black workers spend more time in unemployment, lose their jobs more rapidly, and earn lower wages than white workers. This paper quantifies the contributions of statistical discrimination, as portrayed by negative stereotyping and screening discrimination, to such employment and wage disparities. We develop an equilibrium search model of statistical discrimination with learning based on Moscarini (2005) and estimate it by indirect inference. We show that statistical discrimination alone cannot simultaneously explain the observed differences in residual wages and monthly job loss probabilities between black and white workers. However, a model with negative stereotyping, larger unemployment valuation and faster learning about the quality of matches for black workers can account for these facts. One implication of our findings is that black workers have larger returns to tenure. JEL Codes: J31, J64, J71.
Mots clés Indirect Inference, Job Search, Screening Discrimination, Learning
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Résumé In a competitive business environment, dishonesty can pay. Self-interested executives and managers can have incentive to shade the truth for personal gain. In response, the business community has considered how to commit these executives and managers to a higher ethical standard. The MBA Oath and the Dutch Bankers Oath are examples of such a commitment device. The question we test herein is whether the oath can be used as an effective form of ethics management for future executives/managers-who for our experiment we recruited from a leading French business school-by actually improving their honesty. Using a classic Sender-Receiver strategic game experiment, we reinforce professional identity by pre-selecting the group to which Receivers belong. This allows us to determine whether taking the oath deters lying among future managers. Our results suggest "yes and no." We observe that these future executives/managers who took a solemn honesty oath as a Sender were (a) significantly more likely to tell the truth when the lie was detrimental to the Receiver, but (b) were not more likely to tell the truth when the lie was mutually beneficial to both the Sender and Receiver. A joint product of our design is our ability to measure in-group bias in lying behavior in our population of subjects (comparing behavior of subjects in the same and different business schools). The experiment provides clear evidence of a lack of such bias.
Mots clés Commitment, Lying, In-group bias
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Résumé City size distributions are not strictly Pareto, but upper tails are rather Pareto like (i.e. tails are regularly varying). We examine the properties of the tail exponent estimator obtained from ordinary least squares (OLS) rank size regressions (Zipf regressions for short), the most popular empirical strategy among urban economists. The estimator is then biased towards Zipf’s law in the leading class of distributions. The Pareto quantile–quantile plot is shown to offer a simple diagnostic device to detect such distortions and should be used in conjunction with the regression residuals to select the anchor point of the OLS regression in a data-dependent manner. Applying these updated methods to some well-known data sets for the largest cities, Zipf’s law is now rejected in several cases.
Mots clés Heavy tails, Extreme value index, Rank size regression, Zipf&#039, s law, City size distributions, Regular variation
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Résumé Une présentation synthétique et rigoureuse de l'ensemble des connaissances en statistiques ! Ce livre offre aux étudiants de 1er cycle une introduction aux concepts indispensables en statistiques et à leurs applications. Il comporte douze chapitres traitant de façon simple et claire les sujets majeurs en statistiques : - statistiques descriptives et visualisation des données - analyses factorielles et classification - théorie des sondages - théorie des probabilités- tests d'hypothèses - analyse de la régression - modèles logit et probit - séries temporelles. La compréhension des concepts statistiques présentés ne requiert que la connaissance de l'algèbre. L'un des atouts de ce livre est son caractère appliqué : des exemples concrets illustrent les concepts statistiques présentés dans chaque chapitre. L'objectif est de montrer aux étudiants comment les statistiques participent à la prise de décision des autorités publiques et des chefs d'entreprises. L'accent est mis sur l'utilisation pratique des différents outils statistiques grâce à la présentation des techniques de programmation et des exemples sous R. Un package contenant les codes R des exemples du livre ainsi que les jeux de données est accessible en ligne.
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Résumé Elite-biased democracies are those democracies in which former political incumbents and their allies coordinate to impose part of the autocratic institutional rules in the new political regime. We document that this type of democratic transition is much more prevalent than the emergence of pure (popular) democracies in which the majority decides the new institutional rules. We then develop a theoretical model explaining how an elite-biased democracy may arise in an initially autocratic country. To this end, we extend the benchmark political transition model of Acemoglu and Robinson (2005) along two essential directions. First, population is split into majority versus minority groups under the initial autocratic regime. Second, the minority is an insider as it benefits from a more favourable redistribution by the autocrat. We derive conditions under which elite-biased democracies emerge and characterise them, in particular with respect to pure democracies. https://doi.org/10.1016/j.mathsocsci.2021.03.007
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Résumé This paper is an introduction to the special issue of Mathematical Social Sciences on Advances in growth and macroeconomic dynamics in memory of Carine Nourry.
Mots clés Inequalities and income distribution, Migration and networks, Existence of equilibria, Macroeconomic stability and fluctuations
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