Publications
In this paper, we study the gains and losses incurred during the COVID-19 pandemic. We distinguish between the effects of the pandemic and those of the health measures implemented to reduce the death toll, notably “the lockdown.” Our theoretical model is focused on within-sector firm heterogeneity and involves imperfect competition in a partial equilibrium setting. A comparison between the gains and losses triggered by both the pandemic and the lockdown indicates that an excess profits tax imposed on the “winners” could partly compensate the “losers” of the same sector.
Two main nonpharmaceutical policy strategies have been used in Europe in response to the COVID-19 epidemic: one aimed at natural herd immunity and the other at avoiding saturation of hospital capacity by crushing the curve. The two strategies lead to different results in terms of the number of lives saved on the one hand and production loss on the other hand. Using a susceptible–infected–recovered–dead model, we investigate and compare these two strategies. As the results are sensitive to the initial reproduction number, we estimate the latter for 10 European countries for each wave from January 2020 till March 2021 using a double sigmoid statistical model and the Oxford COVID-19 Government Response Tracker data set. Our results show that Denmark, which opted for crushing the curve, managed to minimize both economic and human losses. Natural herd immunity, sought by Sweden and the Netherlands does not appear to have been a particularly effective strategy, especially for Sweden, both in economic terms and in terms of lives saved. The results are more mixed for other countries, but with no evident trade-off between deaths and production losses.
We analyze theoretically an institution called a “limited-tenure concession” for its ability to induce efficient public goods contribution and common-pool resource extraction. The basic idea is that by limiting the tenure over which an agent can enjoy the public good, but offering the possibility of renewal contingent on ample private provision of that good, efficient provision may be induced. We first show in a simple repeated game setting that limited-tenure concessions can incentivize socially-efficient provision of public goods. We then analyze the ability of this instrument to incentivize the first best provision for common-pool natural resources such as fish and water, thus accounting for spatial connectivity and growth dynamics of the resource. The duration of tenure and the dispersal of the resource play pivotal roles in whether this limited-tenure concession induces the socially optimal private provision. Finally, in a setting with costly monitoring, we discuss the features of a concession contract that ensure first-best behavior, but at least cost to the implementing agency.
In this paper, we consider an abstract regularized method with a skew-symmetric mapping as regularization for solving equilibrium problems. The regularized equilibrium problem can be viewed as a generalized mixed equilibrium problem and some existence and uniqueness results are analyzed in order to study the convergence properties of the algorithm. The proposed method retrieves some existing one in the literature on equilibrium problems. We provide some numerical tests to illustrate the performance of the method. We also propose an original application to Becker’s household behavior theory using the variational rationality approach of human dynamics.
Parmi les priorités affichées dans le programme présidentiel d’Emmanuel Macron figurent l’école, la santé, la dépendance, la police, la justice, l’environnement, l’énergie et la défense. L’absence de l’université dans cette liste est a priori étonnante quand on sait que la dotation publique moyenne par étudiant ne cesse de baisser depuis dix ans, en raison notamment de la hausse des effectifs : tous s’accordent sur ce fait objectif. Lucas Chancel et Thomas Piketty estiment que la dotation publique par étudiant a baissé en termes réels de 16 % entre 2012 et 2022. Le site du ministère de l’Enseignement supérieur ne contredit pas ce constat, en indiquant une baisse nominale de 12 % entre 2011 et 2019. La loi de programmation pour la recherche (LPR) prévoit bien des budgets supplémentaires pour la recherche, à hauteur de 500 millions par an sur les dix prochaines années. À l’horizon du quinquennat qui s’ouvre, si les promesses sont tenues, c’est 0,1 point de PIB en plus pour le financement de la recherche. Mais les sommes qui seraient nécessaires pour nous rapprocher de nos compétiteurs étrangers sont d’un autre ordre de grandeur. Rappelons que la France ne consacre que 1,3 % de son PIB à l’enseignement supérieur, alors que les pays anglo-saxons dépassent les 2 %. Il nous manque 17 milliards par an pour seulement espérer égaler l’Angleterre. Avec 10 milliards de plus par an, on pourrait déjà faire beaucoup, mais nous en sommes loin.
À cela on doit sans doute ajouter que l’évolution de la dette publique et le déficit du budget de l’État nous invitent à un pessimisme renforcé au sujet des dotations publiques dont l’Université pourrait disposer à l’avenir…
This paper examines the effect of weather shocks on violent crime using disaggregated data from Brazilian municipalities over the period 1991–2015. Employing a distributed lag model that takes into account temporal correlations of weather shocks and spatial correlation of crime rates, I document that adverse weather shocks in the form of droughts lead to a significant increase in violent crime in rural regions. This effect appears to persist beyond the growing season and over the medium run in contrast to the conventional view perceiving weather effects as transitory. To explain this persistence, I show that weather fluctuations are positively associated not only with agriculture yields, but also with the overall economic activity. Moreover, evidence shows the dominance of opportunity cost mechanism reflected in the fluctuations of the earnings especially for the agriculture and unskilled workers, giving credence that it is indeed the income that matters and not the general socio-economic conditions. Other factors such as local government budget capacity, (un)-employment, poverty, inequality, and psychological factors do not seem to explain violent crime rates.
I present a model of child development that highlights the effect of parent-child interactions on the formation of skills. Through the parent’s affection, the child learns and builds mental representations of the self as loved and competent. These mental representations shape the child’s noncognitive skills and foster learning. I show that this model provides a unifying explanation for well-established evidence on child development. The model also sheds light on how early exposure to media devices can negatively impact skill acquisition. I discuss implications for the design of policies to reduce inequalities in child development.
This study aims to evaluate people’s willingness to provide their geospatial global positioning system (GPS) data from their smartphones during the COVID-19 pandemic. Based on the self-determination theory, the addition of monetary incentives to encourage data provision may have an adverse effect on spontaneous donation. Therefore, we tested if a crowding-out effect exists between financial and altruistic motivations. Participants were randomized to different frames of motivational messages regarding the provision of their GPS data based on (1) self-interest, (2) pro-social benefit, and (3) monetary compensation. We also sought to examine the use of a negative versus positive valence in the framing of the different armed messages. 1055 participants were recruited from 41 countries with a mean age of 34 years on Amazon Mechanical Turk (MTurk), an online crowdsourcing platform. Participants living in India or in Brazil were more willing to provide their GPS data compared to those living in the United States. No significant differences were seen between positive and negative valence framing messages. Monetary incentives of $5 significantly increased participants’ willingness to provide GPS data. Half of the participants in the self-interest and pro-social arms agreed to provide their GPS data and almost two-thirds of participants were willing to provide their data in exchange for $5. If participants refused the first framing proposal, they were followed up with a “Vickrey auction” (a sealed-bid second-priced auction, SPSBA). An average of $17 bid was accepted in the self-interest condition to provide their GPS data, and the average “bid” of $21 was for the pro-social benefit experimental condition. These results revealed that a crowding-out effect between intrinsic and extrinsic motivations did not take place in our sample of internet users. Framing and incentivization can be used in combination to influence the acquisition of private GPS smartphone data. Financial incentives can increase data provision to a greater degree with no losses on these intrinsic motivations, to fight the COVID-19 pandemic.
In this paper, we introduce a new proximal algorithm for equilibrium problems on a genuine Hadamard manifold, using a new regularization term. We first extend recent existence results by considering pseudomonotone bifunctions and a weaker sufficient condition than the coercivity assumption. Then, we consider the convergence of this proximal-like algorithm which can be applied to genuinely Hadamard manifolds and not only to specific ones, as in the recent literature. A striking point is that our new regularization term have a clear interpretation in a recent “variational rationality” approach of human behavior. It represents the resistance to change aspects of such human dynamics driven by motivation to change aspects. This allows us to give an application to the theories of desires, showing how an agent must escape to a succession of temporary traps to be able to reach, at the end, his desires.
In this paper we introduce a definition of approximate Pareto efficient solution as well as a necessary condition for such solutions in the multiobjective setting on Riemannian manifolds. We also propose an inexact proximal point method for nonsmooth multiobjective optimization in the Riemannian context by using the notion of approximate solution. The main convergence result ensures that each cluster point (if any) of any sequence generated by the method is a Pareto critical point. Furthermore, when the problem is convex on a Hadamard manifold, full convergence of the method for a weak Pareto efficient solution is obtained. As an application, we show how a Pareto critical point can be reached as a limit of traps in the context of the variational rationality approach of stay and change human dynamics.
