Publications

La plupart des informations présentées ci-dessous ont été récupérées via RePEc avec l'aimable autorisation de Christian Zimmermann
Pollution and growth: The role of pension in the efficiency of health and environmental policiesJournal articleArmel Ngami et Thomas Seegmuller, International Journal of Economic Theory, Forthcoming

This paper analyzes the effect of a pay-as-you-go pension system on the evolution of capital and pollution, and on the efficiency of an environmental versus health policy. In an overlapping generations model, we introduce endogenous longevity that depends on pollution and health expenditures. Global dynamics may display multiple balanced growth paths (BGPs). We show that by discouraging savings, a policy that promotes the pension system enlarges the environmental poverty trap. More surprisingly, the environmental policy has contrasting effects according to the significance of the pension system. If it has a small size, a more environmentally-friendly policy enlarges the environmental poverty trap and leads to a rise in capital over pollution at the highest stationary equilibrium. In contrast, in economies where intergenerational solidarity is well developed, capital over pollution decreases at the highest BGP. In such a case, the environmental policy does not necessarily lead to a better longevity and growth.

An evolutionary finance model with short selling and endogenous asset supplyJournal articleRabah Amir, Sergei Belkov, Igor V. Evstigneev et Thorsten Hens, Economic Theory, Forthcoming

Evolutionary finance focuses on questions of “survival and extinction” of investment strategies (portfolio rules) in the market selection process. It analyzes stochastic dynamics of financial markets in which asset prices are determined endogenously by a short-run equilibrium between supply and demand. Equilibrium is formed in each time period in the course of interaction of portfolio rules of competing market participants. A comprehensive theory of evolutionary dynamics of this kind has been developed for models in which short selling is not allowed and asset supply is exogenous. The present paper extends the theory to a class of models with short selling and endogenous asset supply.

Control theory in infinite dimension for the optimal location of economic activity: The role of social welfare functionJournal articleRaouf Boucekkine, Giorgio Fabbri, Salvatore Federico et Fausto Gozzi, Pure and Applied Functional Analysis, Forthcoming

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.

Modeling the impact of product quality on dynamic pricing and advertising policiesJournal articleRégis Y. Chenavaz, Gustav Feichtinger, Richard F. Hartl et Peter M. Kort, European Journal of Operational Research, Forthcoming

The marketing-mix of price–quality and advertising–quality relationship is well studied. Less understood is the price–advertising–quality relationship. This article fills the gap, investigating the interplay between price, advertising, and quality in an optimal control model. Our results generalize the condition of Dorfman–Steiner in a dynamic context. Also, they point to the impact of greater product quality on the dynamic policies of pricing and advertising. Furthermore, a phase diagram analysis shows that quality develops monotonically in time and converges to a unique steady state. We also show that quality investment could either decrease or increase over time but this depends on its effectiveness. Our results spot the profitable opportunities of a firm managing a more complex marketing-mix.

The Welfare Consequences of Centralization: Evidence from a Quasi-Natural Experiment in SwitzerlandJournal articleSarah Flèche, Review of Economics and Statistics, Forthcoming

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.

The impact of ICTs and digitalization on productivity and labor share: evidence from French firmsJournal articleGilbert Cette, Sandra Nevoux et Loriane Py, Economics of Innovation and New Technology, pp. 1-24, Forthcoming

Taking advantage of an original firm-level survey carried out by the Banque de France, we empirically investigate how the employment of ICT specialists (in-house and external) and the use of digital technologies (cloud and big data) have an impact on firm productivity and labor share. Our analysis relies on the survey responses in 2018 of 1,065 French firms belonging to the manufacturing sector and with at least 20 employees. To tackle potential endogeneity issues, we adopt an instrumental variable approach as proposed by Bartik (1991, Who Benefits from State and Local Economic Development Policies? Kalamazoo, MI: W.E. Upjohn Institute for Employment Research.). The results of our cross-section estimations point to a large effect: ceteris paribus, the employment of ICT specialists and the use of digital technologies improve a firm’s labor productivity by about 23% and its total factor productivity by about 17%. Conversely, the employment of in-house ICT specialists and the use of big data both have a detrimental impact on labor share, of about 2.5 percentage points respectively.

To Give or Not to Give? How Do Other Donors React to European Food Aid Allocation?Journal articleNathalie Ferrière, The European Journal of Development Research, Forthcoming

Using a change in EU food aid policy in 1996 as an instrument for EU food aid allocation, I investigate how other donors react to the EU’s food aid allocation. At that time, the EU suddenly divided by two the number of its food aid recipients. On average, other donors imitate the EU at both extensive and intensive margins. Donors’ reactions are heterogeneous: European countries and Canada herd the EU, while the World Food Programme substitutes. The USA do not react. Those results can be explained by competition for relative impact and information effects. For a recipient country who constantly received food aid from the EU before 1996, the number of donors decreases by almost 0.5. This behavior reinforces the problem of orphan and darling recipients.

Evaluating education systemsJournal articleNicolas Gravel, Edward Levavasseur et Patrick Moyes, Applied Economics, pp. 1-31, Forthcoming

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.

A new regularization of equilibrium problems on Hadamard manifolds. Applications to theories of desiresJournal articleJr. P. A. Soares, J.X. Cruz Neto, G. C. Bento et Antoine Soubeyran, Annals of Operations Research, Forthcoming
Online study of health professionals about their vaccination attitudes and behavior in the COVID-19 era: addressing participation biasJournal articlePierre Verger, Dimitri Scronias, Yves Fradier, Malika Meziani et Bruno Ventelou, Human Vaccines & Immunotherapeutics, pp. 1-6, Forthcoming

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.