Publications

La plupart des informations présentées ci-dessous ont été récupérées via RePEc avec l'aimable autorisation de Christian Zimmermann
Interpretable Machine Learning Using Partial Linear Models*Journal articleEmmanuel Flachaire, Sullivan Hué, Sébastien Laurent et Gilles Hacheme, Oxford Bulletin of Economics and Statistics, Volume 69, 2023

Despite their high predictive performance, random forest and gradient boosting are often considered as black boxes which has raised concerns from practitioners and regulators. As an alternative, we suggest using partial linear models that are inherently interpretable. Specifically, we propose to combine parametric and non-parametric functions to accurately capture linearities and non-linearities prevailing between dependent and explanatory variables, and a variable selection procedure to control for overfitting issues. Estimation relies on a two-step procedure building upon the double residual method. We illustrate the predictive performance and interpretability of our approach on a regression problem.

Judicial CaptureJournal articleSultan Mehmood et Bakhtawar Ali, The Economic Journal, pp. uead106, 2023

We use data from Pakistan to establish a reciprocal exchange relationship between the judiciary and the government. We document large transfers in the form of expensive real estate from the government to the judiciary, and reciprocation in the form of pro-government rulings from the judiciary to the government. Our estimates indicate that the allocation of houses to judges increases pro-government rulings and reduces decisions on case merits. The allocation also incurs a cumulative cost of 0.03% of GDP to the government. However, it allows the government to expropriate additional land worth 0.2% of GDP in one year.

Mental health effects of COVID-19 lockdowns: A Twitter-based analysisJournal articleSara Colella, Frédéric Dufourt, Vincent A. Hildebrand et Rémi Vivès, Economics & Human Biology, Volume 51, pp. 101307, 2023

We use a distinctive methodology that leverages a fixed population of Twitter users located in France to gauge the mental health effects of repeated lockdown orders. To do so, we derive from our population a mental health indicator that measures the frequency of words expressing anger, anxiety and sadness. Our indicator did not reveal a statistically significant mental health response during the first lockdown, while the second lockdown triggered a sharp and persistent deterioration in all three emotions. Our estimates also show a more severe deterioration in mental health among women and younger users during the second lockdown. These results suggest that successive stay-at-home orders significantly worsen mental health across a large segment of the population. We also show that individuals who are closer to their social network were partially protected by this network during the first lockdown, but were no longer protected during the second, demonstrating the gravity of successive lockdowns for mental health.

Do foreign MNEs alleviate multidimensional poverty in developing countries?Journal articleJulien Hanoteau, Eurasian Business Review, Volume 13, Issue 4, pp. 719-749, 2023

This study investigates the effects of the investment-based presence of multinational enterprises (MNEs) on poverty in developing countries. The relationship is decomposed into different pathways corresponding to various facets of firms’ presence and activities, and monetary and multidimensional poverty. We hypothesize that depending on the pathways, the effects can be positive or negative in terms of poverty alleviation, and an overall conclusion has to be nuanced. The hypotheses are tested across 431 Indonesian administrative districts, observed in 2008, 2014 and 2018. Pooled instrumental variable regressions show that a higher presence of foreign MNEs does not reduce the number of people below the poverty line. It raises the depth and severity of poverty, and the population is also more exposed to pollutions. These results inform the ongoing debate, and offer important implications for policy makers eager to attract foreign direct investments, as well as for MNEs’ managers concerned with social responsibility and achieving sustainable development goals in host developing countries.

Stated preferences outperform elicited preferences for predicting reported compliance with COVID-19 prophylactic measuresJournal articleIsmael Rafai, Thierry Blayac, Dimitri Dubois, Sebastien Duchêne, Phu Nguyen-Van, Bruno Ventelou et Marc Willinger, Journal of Behavioral and Experimental Economics, Volume 107, pp. 102089, 2023

This article studies the behavioral and socio-demographic determinants of reported compliance with prophylactic measures against COVID-19: barrier gestures, lockdown restrictions and mask wearing. The study contrasts two types of measures for behavioral determinants: experimentally elicited preferences (risk tolerance, time preferences, social value orientation and cooperativeness) and stated preferences (risk tolerance, time preferences, and the GSS trust question). Data were collected from a representative sample of the inland French adult population (N=1154) surveyed during the first lockdown in May 2020, and the experimental tasks were carried out on-line. The in-sample and out-of-sample predictive power of several regression models - which vary in the set of variables that they include - are studied and compared. Overall, we find that stated preferences are better predictors of compliance with these prophylactic measures than preferences elicited through incentivized experiments: self-reported level of risk, patience and trust are predicting compliance, while elicited measures of risk-aversion, patience, cooperation and prosociality did not.

Financially sustainable optimal currency areasJournal articleAndré Cartapanis, Marie-Hélène Gagnon et Céline Gimet, Finance Research Letters, Volume 58, Issue Part A, pp. 104059, 2023

In current economic conditions, financial stability is paramount to the proper functioning of open markets. Financial stability must be balanced with financial flexibility. This relationship is deeply affected by financial fragmentation. This is why Central Banks have focused on these issues in the last decade in particular. Both financial stability and financial fragmentation have unintended consequences on optimal currency areas. In this paper, we survey the original optimal currency areas literature and relate it with the new literature on financial stability and financial fragmentation. We highlight the importance of new macroprudential policies both at the national and regional levels.

Stated preferences outperform elicited preferences for predicting reported compliance with Covid-19 prophylactic measuresJournal articleIsmael Rafai, Thierry Blayac, Dimitri Dubois, Sebastien Duchêne, Phu Nguyen-Van, Bruno Ventelou et Marc Willinger, Journal of Behavioral and Experimental Economics, Volume 107, pp. 102089, 2023

This article studies the behavioral and socio-demographic determinants of reported compliance with prophylactic measures against COVID-19: barrier gestures, lockdown restrictions and mask wearing. The study contrasts two types of measures for behavioral determinants: experimentally elicited preferences (risk tolerance, time preferences, social value orientation and cooperativeness) and stated preferences (risk tolerance, time preferences, and the GSS trust question). Data were collected from a representative sample of the inland French adult population (N=1154) surveyed during the first lockdown in May 2020, and the experimental tasks were carried out on-line. The in-sample and out-of-sample predictive power of several regression models - which vary in the set of variables that they include - are studied and compared. Overall, we find that stated preferences are better predictors of compliance with these prophylactic measures than preferences elicited through incentivized experiments: self-reported level of risk, patience and trust are predicting compliance, while elicited measures of risk-aversion, patience, cooperation and prosociality did not.

Regulatory harmonization with the European Union: opportunity or threat to Moroccan firms?Journal articlePatricia Augier, Olivier Cadot et Marion Dovis, Review of World Economics, 2023

This paper combines a database on non-tariff measures (NTMs) with Morocco’s firm-level census to explore the effect of regulatory harmonization with the E.U. on firms’ outcomes. Exploiting cross-sectoral variation in the timing and extent of regulatory harmonization, we find that harmonization waves correlate with rises in productivity, with higher markups and with greater numbers of exporting firms. These effects were reinforced by an induced market-structure change: harmonization temporarily protected the Moroccan market from competition from low-end producers in other developing countries, who took time to adapt. We identify these effects through changes in both trade patterns and firm-level outcomes.

On inexact versions of a quasi-equilibrium problem: a Cournot duopoly perspectiveJournal articleE. L. Dias Júnior, P. J. S. Santos, A. Soubeyran et J. C. O. Souza, Journal of Global Optimization, 2023

This paper has two parts. In the mathematical part, we present two inexact versions of the proximal point method for solving quasi-equilibrium problems (QEP) in Hilbert spaces. Under mild assumptions, we prove that the methods find a solution to the quasi-equilibrium problem with an approximated computation of each iteration or using a perturbation of the regularized bifunction. In the behavioral part, we justify the choice of the new perturbation, with the help of the main example that drives quasi-equilibrium problems: the Cournot duopoly model, which founded game theory. This requires to exhibit a new QEP reformulation of the Cournot model that will appear more intuitive and rigorous. It leads directly to the formulation of our perturbation function. Some numerical experiments show the performance of the proposed methods.

The Academic Market and The Rise of Universities in Medieval and Early Modern Europe (1000–1800)Journal articleDavid de la Croix, Frédéric Docquier, Alice Fabre et Robert Stelter, Journal of the European Economic Association, pp. jvad061, 2023

We argue that market forces shaped the geographic distribution of upper-tail human capital across Europe during the Middle Ages, and contributed to bolstering universities at the dawn of the Humanistic and Scientific Revolutions. We build a unique database of thousands of scholars from university sources covering all of Europe, construct an index of their ability, and map the academic market in the medieval and early modern periods. We show that scholars tended to concentrate in the best universities (agglomeration), that better scholars were more sensitive to the quality of the university (positive sorting) and migrated over greater distances (positive selection). Agglomeration, selection, and sorting patterns testify to an integrated academic market, made possible by the use of a common language (Latin).