Publications
In this paper, we consider an abstract optimal control problem with state constraint. The methodology relies on the employment of the classical dynamic programming tool considered in the infinite dimensional context. We are able to identify a closed-form solution to the induced Hamilton-Jacobi-Bellman (HJB) equation in infinite dimension and to prove a verification theorem, also providing the optimal control in closed loop form. The abstract problem can be seen an abstract formulation of a PDE optimal control problem and is motivated by an economic application in the context of continuous spatiotemporal growth models with capital di usion, where a social planner chooses the optimal location of economic activity across space by maximization of an utilitarian social welfare function. From the economic point of view, we generalize previous works by considering a continuum of social welfare functions ranging from Benthamite to Millian functions. We prove that the Benthamite case is the unique case for which the optimal stationary detrended consumption spatial distribution is uniform. Interestingly enough, we also find that as the social welfare function gets closer to the Millian case, the optimal spatiotemporal dynamics amplify the typical neoclassical dilution population size effect, even in the long-run.
Comment mesurer le plus finement possible l'accélération ou la décélération d'une épidémie ?
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.
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.
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.
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.
Statistiques pour l'économie et la gestion offre une présentation synthétique et rigoureuse de l’ensemble des connaissances en statistiques !
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.
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.
Bien que les canicules soient les événements climatiques extrêmes les plus importants en termes de mortalité, leurs impacts sont rarement considérés sous un angle économique. Cette méconnaissance, couplée à une perception du risque qui demeure faible, s’avère un frein à l’action en matière d’adaptation. Nous proposons une évaluation monétaire des impacts sanitaires des canicules en France métropolitaine entre 2015 et 2020.
Méthode –
Les indicateurs sanitaires suivis dans le cadre du Plan national canicule ont été utilisés pour appréhender les coûts des passages aux urgences et consultations SOS Médecins pour une sélection de causes liées à la chaleur. La mortalité en excès et la perte d’espérance de vie ont également été valorisées économiquement, ainsi que la perte de bien-être due aux restrictions d’activité. Une approche fondée sur le coût total de la maladie (coût direct, indirects et intangibles) et le consentement à payer a été utilisée.
Résultats –
Entre 2015 et 2020, les impacts sanitaires étudiés représentent au total, selon la méthode choisie, autour de 22 ou de 37 milliards €. La mortalité en excès est majoritaire (16 milliards € lorsqu’exprimée en années de vie perdues, ou 30 milliards € lorsqu’exprimée à partir des décès en excès) et la restriction d’activité est évaluée à environ 6 milliards €.
Conclusions –
Cette étude permet de mieux objectiver l’impact économique de ces événements climatiques extrêmes. Dans un contexte où les évolutions climatiques annoncent un accroissement des températures et des phénomènes de vagues de chaleur, pouvant conduire à une aggravation des impacts, ces résultats obtenus soulignent encore l’importance et l’urgence de mesures d’action permettant de renforcer l’adaptation aux canicules.
