Publications

Résumé The aim of this paper is to study the interplay between long term productive investments and more short term and liquid speculative ones. A three-period lived overlapping generations model allows us to make this distinction. Agents have a portfolio decision. When young, they can invest in human capital that is a productive long term investment that provides a return during the following two periods. When young or in the middle age, they can invest in a bubble. Young individuals can also borrow on a credit market to finance the productive investment. However, the amount borrowed is limited by a credit constraint. We show that the existence of a stationary bubble raises productive investment and production when the bubleless economy is credit constrained and dynamically efficient. Indeed, young agents sell short the bubble to increase productive investments, whereas traders at middle age transfer wealth to old age. The bubble allows to relax the credit constraint. We outline that a permanent technological shock inducing either a larger return of capital in the short term or a similar increase in the return of capital in both periods raises productive capital, production and the bubble size. We use our framework to discuss the effect on the occurrence of bubbles of financial regulation and fiscal policy.
Mots clés Overlapping generations, Short sellers, Credit, Vintage capital, Efficiency, Bubble
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Résumé Les effets sur la santé dits de long terme pose des difficultés particulières dans les évaluations économiques. En effet, puisque ces effets sont dues à une exposition cumulée à des facteurs de risque, il faut s'attendre à des délais entre la date de mise en oeuvre d'une politique de réduction de ces facteurs de risque et le moment où la totalité des bénéfices sanitaires espérés seront obtenus. Nous développons une méthodologie qui permet d'estimer ces délais et l'évolution des bénéfices obtenus. Nous appliquons cette méthodologie au cas d'une politique de réduction de la pollution de l'air. Le résultat principal est que la prise en compte de ces délais conduit à diviser par un facteur 1,6 à 2,5 les bénéfices. Il apparaît aussi que le taux d'actualisation a un effet qui dépend de la méthode de valorisation monétaire des effets sanitaires.
Mots clés Air pollution, Long term mortality, Cost-benefit analysis, Discounting, Life expectancy, Analyse coût-bénéfice, Effet de long terme, Pollution de l&#039, air, Actualisation, Espérance de vie, Coûts sanitaires, Mortalité
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Résumé Les récentes mutations du mécénat d’entreprise invitent à interroger la responsabilité culturelle de l’entreprise, celle-ci est-elle toujours intégrée au sein de la Responsabilité Sociétale de l’Entreprise (RSE), ou constitue-t-elle désormais un pôle à part ? Dans cette perspective, l’ouvrage pluridisciplinaire, Quelle responsabilité culturelle pour l’entreprise ? associant économistes, juristes, littéraires et professionnels des secteurs concernés, permet de mieux comprendre ce qui se joue aujourd’hui dans la relation du chef d’entreprise mécène à l’artiste.
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Résumé The stability of Nash equilibria has often been studied by examining the asymptotic behavior of the best-response dynamics. This is generally done in games where interactions are global and equilibria are isolated. In this paper, we analyze stability in contexts where interactions are local and where there are continua of equilibria. We focus on the public good game played on a network, where the set of equilibria is known to depend on the network structure (Bramoullé and Kranton, 2007), and where, as we show, continua of equilibria often appear. We provide necessary and sufficient conditions for a component of Nash equilibria to be asymptotically stable vis-à-vis the best-response dynamics. Interestingly, we demonstrate that these conditions relate to the structure of the network in a simple way. We also provide corresponding results for several dynamical systems related to the best response.
Mots clés Stability, Public good games, Best-response dynamics
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Résumé Economists typically view personal income taxes as a tradeoff between distortionary effects on labour supply and desirable effects on the income distribution. However, when wages deviate from marginal product, there is an efficiency rationale for income taxation. In the empirically relevant setting of wage bargaining within hierarchical firms, the efficiency case for taxing the manager at the top of the firm depends on a “job-creation” effect: if wages are too low and increased labour supply allows managers to supervise larger firms and thus collect larger rents, they will work too hard to create jobs at their firm. It may then be efficient to tax the “job creators” because of their job-creation activity. If bargaining compresses the wage distribution for workers, the efficient tax schedule is V-shaped and deviates significantly from zero in a model calibrated to the U.S. income distribution. For a planner with redistributive motives, wage bargaining similarly raises optimal marginal tax rates at the top and bottom of the distribution, while decreasing them in the middle.
Mots clés Job creators, Hierarchical firms, Wage bargaining, Efficiency, Optimal Income Taxation
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Résumé BACKGROUND: In 2016, countries agreed on a Fast-Track strategy to "end the AIDS epidemic by 2030". The treatment and prevention components of the Fast-Track strategy aim to markedly reduce new HIV infections, AIDS-related deaths and HIV-related discrimination. This study assesses the economic returns of this ambitious strategy. METHODS: We estimated the incremental costs, benefits and economic returns of the Fast-Track scenario in low- and middle-income countries, compared to a counterfactual defined as maintaining coverage of HIV-related services at 2015 levels. The benefits are calculated using the full-income approach, which values both the changes in income and in mortality, and the productivity approach. FINDINGS: The incremental costs of the Fast-Track scenario over the constant scenario for 2017-2030 represent US$86 billion or US$13.69 per capita. The full-income valuation of the incremental benefits of the decrease in mortality amounts to US$88.14 per capita, representing 6.44 times the resources invested for all countries. These returns on investment vary by region, with the largest return in the Asia-Pacific region, followed by Eastern and Southern Africa. Returns using the productivity approach are smaller but ranked similarly across regions. INTERPRETATION: In all regions, the economic and social value of the additional life-years saved by the Fast-Track approach exceeds its incremental costs, implying that this strategy for ending the AIDS epidemic is a sound economic investment.
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Résumé Background: Measuring the quality and performance of health care is a major challenge in improving the efficiency of a health system. Patient experience is one important measure of the quality of health care, and the use of patient-reported experience measures (PREMs) is recommended. The aims of this project are 1) to develop item banks of PREMs that assess the quality of health care for adult patients with psychiatric disorders (schizophrenia, bipolar disorder, and depression) and to validate computerized adaptive testing (CAT) to support the routine use of PREMs; and 2) to analyze the implementation and acceptability of the CAT among patients, professionals, and health authorities. Methods: This multicenter and cross-sectional study is based on a mixed method approach, integrating qualitative and quantitative methodologies in two main phases: 1) item bank and CAT development based on a standardized procedure, including conceptual work and definition of the domain mapping, item selection, calibration of the item bank and CAT simulations to elaborate the administration algorithm, and CAT validation; and 2) a qualitative study exploring the implementation and acceptability of the CAT among patients, professionals, and health authorities. Discussion: The development of a set of PREMs on quality of care in mental health that overcomes the limitations of previous works (ie, allowing national comparisons regardless of the characteristics of patients and care and based on modern testing using item banks and CAT) could help health care professionals and health system policymakers to identify strategies to improve the quality and efficiency of mental health care.
Mots clés COM, PARIS team
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Résumé Oath-taking for senior executives has been promoted as a mean to enhance honesty within and towards organizations. Herein we explore whether people who voluntarily sign a solemn truth-telling oath are more committed to sincere behavior when offered the chance to lie. We design an experiment to test how the oath affects truth-telling in two contexts: a neutral context replicating the typical experiment in the literature, and a "loaded" context in which we remind subjects that "a lie is a lie." We consider four payoff configurations, with differential monetary incentives to lie, implemented as within-subjects treatment variables. The results are reinforced by robustness investigations in which each subject made only one lying decision. Our results show that the oath reduces lying, especially in the loaded environment-falsehoods are reduced by fifty percent. The oath, however, have a weaker effect on lying in the neutral environment. The oath did affect decision times in all instances: the average person takes significantly more time deciding whether to lie under oath.
Mots clés Lies, Deception, Laboratory Experiment, Truth-telling oath
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Résumé Nous étudions la faisabilité d’un impôt foncier unique (IFU) sur le patrimoine foncier et immobilier des ménages qui remplacerait tous les impôts existants portant sur ce type de patrimoine, en particulier, la taxe foncière, l’IFI, les DMTO, la taxe sur les plus-values immobilières et l’impôt sur les revenus fonciers perçus par les propriétaires bailleurs. La valeur du patrimoine net de la dette immobilière, moins un abattement sur la valeur de la résidence principale de 50 000 euros, serait taxée au taux de 1 % jusqu’au seuil de l’IFI (soit 1,3 million d’euros) et à hauteur de 1,5 % au-delà. Les recettes seraient partagées entre l’État et les collectivités territoriales au moyen d’un fonds de péréquation. Après avoir présenté les raisons qui légitiment notre proposition de réforme, nous procédons à une première évaluation du rendement de l’impôt et du profil de la charge fiscale en fonction du revenu, de la taille familiale et de l’âge en mobilisant l’enquête Patrimoine de l’INSEE. La décorrélation partielle des revenus et des patrimoines immobiliers permet difficilement d’en faire un grand impôt de rendement, même si la recette fiscale espérée est équivalente à la recette perdue des impôts remplacés. Un plafonnement de l’IFU en termes de revenu disponible briderait assez rapidement son rendement.
Mots clés Impôt sur le capital, Impôts fonciers, Immobilier, Réforme, Redistribution, Impôt sur le capital
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