Publications

Résumé In this article we propose a theoretical model to better comprehend the effect of gun laws on violent property crime. We assume that a violent encounter between a criminal and a victim is costly to both, and we uncover two types of equilibria: a pure strategy violent equilibrium and a mixed strategy equilibrium where the criminal is deterred with strictly positive probability. The effect of a relaxation of gun laws is shown to be conditional on both initial gun laws and on the relative improvement of the victims’ defense capacity relative to the criminals’ offense capacity. We uncover a potentially inverted U-shaped relationship between gun laws leniency and investments in violent activities which helps reconciling seemingly contradictory empirical findings.
Mots clés Deterrence, Gun laws, Crime, Dissuasion, Contrôle des armes à feu, Crime
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Résumé By using a pre-order principle in [Qiu JH. A pre-order principle and set-valued Ekeland variational principle. J Math Anal Appl. 2014;419:904–937], we establish a general equilibrium version of set-valued Ekeland variational principle (denoted by EVP), where the objective function is a set-valued bimap defined on the product of left-complete quasi-metric spaces and taking values in a quasi-ordered linear space, and the perturbation consists of a cone-convex subset of the ordering cone multiplied by the quasi-metric. Moreover, we obtain an equilibrium EVP, where the perturbation contains a σ-convex subset and the quasi-metric. From the above two general EVPs, we deduce several interesting corollaries, which extend and improve the related known results. Several examples show that the obtained set-valued EVPs are new. Finally, applying the above EVPs to organizational behavior sciences, we obtain some interesting results on organizational change and development with leadership. In particular, we show that the existence of robust organizational traps.
Mots clés Robust trap problem, Caristi&#039, s fixed point theorem, Pre-order principle, Quasi-metric space, Equilibrium version of Ekeland variational principle
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Résumé Disparities in physicians' geographical distribution lead to highly unequal access to healthcare, which may impact quality of care in both high and low-income countries. This paper uses a 2013-2014 nationally representative survey of French general practitioners (GPs) matched with corresponding administrative data to analyze the effects of practicing in an area with weaker medical density. To avoid the endogeneity issue on physicians' choice of the location, we enriched our variable of interest, practicing in a relatively underserved area, with considering changes in medical density between 2007 and 2013, thus isolating GPs who only recently experienced a density decline (identifying assumption). We find that GPs practicing in underserved areas do shorter consultations and tend to substitute time-consuming procedures with alternatives requiring fewer human resources, especially for pain management. Results are robust to considering only GPs newly exposed to low medical density. Findings suggest a significant impact of supply-side shortages on the mix of healthcare services used to treat patients, and point to a plausible increased use of painkillers, opioids in particular.
Mots clés France, Opioids, Health workforce, Medically underserved area, General practitioners, Prescriptions
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Résumé Fêtes de réveillon en petit comité ou annulées, familles dispersées et isolées, autoconfinement, confinements locaux, partiels ou généralisés, couvre-feu, restrictions de déplacement, fermeture des frontières, incertitudes quant à la réouverture de certains secteurs : la France, comme de nombreux autres pays du monde, a fait face à une série de restrictions pour tenter d'endiguer l'épidémie. Si chaque type de mesures/restrictions a sa propre efficacité dans le contrôle de la dynamique épidémiologique, ces dernières doivent également être évaluées en fonction de leur acceptabilité par la population. À l'heure où les décideurs se posent la question de ré-évaluer les mesures restrictives pour éviter un rebond de l'épidémie, les préférences des populations devraient compter dans la décision publique.
Mots clés Confinement, Epidémie de Covid-19, Mesure restrictive
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Résumé This paper analyzes the behavior of cross-country growth rates with respect to resource abundance and dependence. We reject the linear model that is commonly used in growth regressions in favor of a multiple-regime alternative. Using a formal sample-splitting method, we find that countries exhibit different behaviors with respect to natural resources depending on their initial level of development. In high-income countries, natural resources play only a minor role in explaining the differences in national growth rates. On the contrary, in low-income countries, abundance seems to be a blessing but dependence restricts growth.
Mots clés Natural resources, Threshold regressions, Growth, Resource curse
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Résumé This study investigates U.S. churches' response to the SARS-CoV-2 pandemic by looking at their public Facebook posts. For religious organizations, in-person gatherings are at the heart of their activities. Yet religious in-person gatherings have been identified as some of the early hot spots of the pandemic, but there has also been controversy over the legitimacy of public restrictions on such gatherings. Our sample contains information on church characteristics and Facebook posts for nearly 4000 churches that posted at least once in 2020. The share of churches that offer an online church activity on a given Sunday more than doubled within two weeks at the beginning of the pandemic (the first half of March 2020) and stayed well above baseline levels. Online church activities are positively correlated with the local pandemic situation at the beginning, but uncorrelated with most state interventions. After the peak of the first wave (mid April), we observe a slight decrease in online activities. We investigate heterogeneity in the church responses and find that church size and worship style explain differences consistent with churches facing different demand and cost structures. Local political voting behavior, on the other hand, explains little of the variation. Descriptive analysis suggests that overall online activities, and the patterns of heterogeneity, remain unchanged through end-November 2020.
Mots clés Social media, Church, Covid-19 pandemic, Facebook
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Résumé This paper analyzes the link between asset bubbles, endogenous labor and capital. First, we explicitly and theoretically derive the conditions to have a crowding-in effect of the bubble, i.e. higher levels of capital and labor. Second, the utility function we consider shows that this result does not require an arbitrarily high elasticity of intertemporal substitution in consumption.
Mots clés Overlapping generations, Endogenous labor, Crowding-in effect, Asset bubbles
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Résumé This study compares GDP per capita levels and growth rates across 17 advanced economies over the period 1890–2013 using an accounting breakdown and runs Phillips and Sul (Econometrica 75(6):1771–1855, 2007) convergence tests. An overall convergence process has been at work among advanced economies, mainly after WWII, driven mostly by capital intensity and then TFP, while trends in hours worked and employment rates are disparate. However, this convergence process came to a halt during technology shocks, during the two world wars and since the 1990s, with the convergence of advanced economies stopping far from the level of US GDP per capita.
Mots clés Global history, Technological change, Convergence, Productivity, GDP per capita
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Résumé Immigrants are disproportionately employed in agriculture and construction, sectors with relatively high injury rates. What pushes immigrants to accept riskier and more strenuous work conditions? We propose a circular model and show that differences in average work conditions borne by natives and immigrants are driven by both preferences and unearned income. Using French data we find that, in line with the model’s predictions, (i) rigid wages are associated with a larger immigrant-native gap in work conditions; (ii) high unearned income individuals benefit on average from better work conditions; (iii) for immigrants and natives with high unearned income, differences in demographic characteristics explain part of the immigrant-native gap in work conditions. In contrast, the gap largely persists among low unearned income people even once we have imposed identical demographic composition among them. This suggests that there must be other factors that influence preferences over work conditions and that are missing in our empirical analysis.
Mots clés Composition effects, Preferences, Outside employment opportunities, Work conditions, Immigrants
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Résumé This paper provides an empirical assessment of the effect of income inequality on credit dynamics in 12 advanced economies over the period 1948-2015. We use foreign Communist influence as an instrument to identify exogenous variation in inequality and estimate the dynamic effect of a top income shock on credit over GDP. The results suggest that the evolution of top incomes has persistent effects on credit expansion, especially for mortgage and business loans.
Mots clés Top income shares, Income inequality, Finance, Credit
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