Publications

La plupart des informations présentées ci-dessous ont été récupérées via RePEc avec l'aimable autorisation de Christian Zimmermann
The Creation and Evolution of the Donor Funded Market for Antimalarials and the Growing Role of Southern FirmsJournal articleFabienne Orsi, Sauman Singh et Luis Sagaon-Teyssier, Science, Technology and Society, Volume 23, Issue 3, pp. 349-370, 2018

Since the early 2000s, the question of access to medicines at affordable prices for Southern populations has appeared as one of the major challenges for the international governance of health. But what is at stake is the creation of market for medicines in the global South, particularly countries in the Sub-Saharan Africa. These markets are new in nature in the sense that they are driven by international organisations where Southern firms, especially from India, occupy an increasingly important position. However, the specificity of these markets and the way they are constituted have been little analysed. In this article, we suggest focusing the attention on the constitution of the market of antimalarial drugs and highlighting the role played by Southern firms in this market. Our study focuses on the public sector market of antimalarial drugs. We provide an institutional and quantitative analysis of the creation of this public market. We then discuss the growing importance of the Southern firms, mainly Indian and Chinese, in this market.

Is the emergence of new sovereign wealth funds a fashion phenomenon?Journal articleJeanne Amar, Christelle Lecourt et Valerie Kinon, Review of World Economics, Volume 154, Issue 4, pp. 835-873, 2018

The paper deals with the important financial policy issue of the decision for a country to establish a sovereign wealth fund (SWF). Using a large-scale database, we analyze the economic, political and institutional factors that should be considered in such a decision. In particular, we test if the emergence of SWFs and more specifically of a specific type of SWFs can be explained by the following factors: the excess foreign exchange reserves due to natural resources rents or persistent current account surpluses; the volatility of commodity prices; the appreciation of the real exchange rate leading to the “Dutch Disease” effect and the governance of the country. The results suggest that countries with excess foreign exchange reserves, which are dependent on a commodity and which suffer from an appreciation of the real exchange rate are more likely to create a fund. We also find that commodity-based funds tend to be established in low democratic countries. Finally, our results suggest that the factors driving SWFs creation are different depending on the origin of the funding (commodity or non-commodity) and the macroeconomic objective(s) assigned to the fund. Our results may be of interest for policymakers debating whether or not it can be optimal for the country to establish a SWF.

A Review on Variable Selection in Regression AnalysisJournal articleLoann David Deni Desboulets, Econometrics, Volume 6, Issue 4, pp. 45, 2018

In this paper, we investigate several variable selection procedures to give an overview of the existing literature for practitioners. “Let the data speak for themselves” has become the motto of many applied researchers since the number of data has significantly grown. Automatic model selection has been promoted to search for data-driven theories for quite a long time now. However, while great extensions have been made on the theoretical side, basic procedures are still used in most empirical work, e.g., stepwise regression. Here, we provide a review of main methods and state-of-the art extensions as well as a topology of them over a wide range of model structures (linear, grouped, additive, partially linear and non-parametric) and available software resources for implemented methods so that practitioners can easily access them. We provide explanations for which methods to use for different model purposes and their key differences. We also review two methods for improving variable selection in the general sense.

Networked innovation and coalition formation: the effect of group-based social preferencesJournal articleTom Dedeurwaerdere, Paolo Melindi-Ghidi et Willem Sas, Economics of Innovation and New Technology, Volume 27, Issue 7, pp. 577-593, 2018

In this paper, we study the production and dissemination of public knowledge goods, such as technological knowledge, generated by a network of voluntarily cooperating innovators. We develop a private-collective model of public knowledge production in networked innovation systems, where group-based social preferences have an impact on the coalition formation of developers. Our model builds on the large empirical literature on voluntary production of pooled public knowledge goods, including source code in communities of software developers or data provided to open access data repositories. Our analysis shows under which conditions social preferences, such as ‘group belonging’ or ‘peer approval’, influence the stable coalition size, as such rationalising several stylized facts emerging from large-scale surveys of open-source software developers, previously unaccounted for. Furthermore, heterogeneity of social preferences is added to the model to study the formation of stable but mixed coalitions.

Variational principles, completeness and the existence of traps in behavioral sciencesJournal articleTruong Q. Bao, S. Cobzaş et Antoine Soubeyran, Annals of Operations Research, Volume 269, Issue 1, pp. 53-79, 2018

In this paper, driven by Behavioral applications to human dynamics, we consider the characterization of completeness in pseudo-quasimetric spaces in term of a generalization of Ekeland’s variational principle in such spaces, and provide examples illustrating significant improvements to some previously obtained results, even in complete metric spaces. At the behavioral level, we show that the completeness of a space is equivalent to the existence of traps, rather easy to reach (in a worthwhile way), but difficult (not worthwhile to) to leave. We first establish new forward and backward versions of Ekeland’s variational principle for the class of strict-decreasingly forward (resp. backward)-lsc functions in pseudo-quasimetric spaces. We do not require that the space under consideration either be complete or to enjoy the limit uniqueness property since, in a pseudo-quasimetric space, the collections of forward-limits and backward ones of a sequence, in general, are not singletons.

Individual Uncertainty About LongevityJournal articleBrigitte Dormont, Anne-Laure Samson, Marc Fleurbaey, Stéphane Luchini et Erik Schokkaert, Demography, Volume 55, Issue 5, pp. 1829-1854, 2018

This article presents an assessment of individual uncertainty about longevity. A survey performed on 3,331 French people enables us to record several survival probabilities per individual. On this basis, we compute subjective life expectancies (SLE) and subjective uncertainty regarding longevity (SUL), the standard deviation of each individual’s subjective distribution of her or his own longevity. It is large and equal to more than 10 years for men and women. Its magnitude is comparable to the variability of longevity observed in life tables for individuals under 60, but it is smaller for those older than 60, which suggests use of private information by older respondents. Our econometric analysis confirms that individuals use private information—mainly their parents’ survival and longevity—to adjust their level of uncertainty. Finally, we find that SUL has a sizable impact, in addition to SLE, on risky behaviors: more uncertainty on longevity significantly decreases the probability of unhealthy lifestyles. Given that individual uncertainty about longevity affects prevention behavior, retirement decisions, and demand for long-term care insurance, these results have important implications for public policy concerning health care and retirement.

Econometrics and Income InequalityJournal articleMartin Biewen et Emmanuel Flachaire, Econometrics, Volume 6, Issue 4, pp. 42, 2018

It is well-known that, after decades of non-interest in the theme, economics has experienced a proper surge in inequality research in recent years. [...]

Conditional expected utility criteria for decision making under ignorance or objective ambiguityJournal articleNicolas Gravel, Thierry Marchant et Arunava Sen, Journal of Mathematical Economics, Volume 78, Issue C, pp. 79-95, 2018

We provide an axiomatic characterization of a family of criteria for ranking completely uncertain and/or ambiguous decisions. A completely uncertain decision is described by the set of all its consequences (assumed to be finite). An ambiguous decision is described as a set of possible probability distributions over a set of prizes. Every criterion in the family compares sets on the basis of their conditional expected utility , for some “likelihood” function taking strictly positive values and some utility function both having the universe of alternatives as their domain.

When do imperfectly competitive firms maximize profits? The lessons from a simple general equilibrium model with shareholders’ votingJournal articleRim Lahmandi-Ayed et Didier Laussel, Journal of Mathematical Economics, Volume 78, Issue C, pp. 6-12, 2018

We consider a general equilibrium model with vertical preferences, where workers and consumers are differentiated, respectively, by their sensitivity to effort and their intensity of preference for quality. We consider a monopoly of which the shares are owned by a fraction of the general population. The price is determined through a vote among all the shareholders. We identify necessary and sufficient conditions for (i) an absolute (relative) majority to vote for the profit maximizing price; (ii) an absolute (relative) majority to vote for a different price. We argue that the more concentrated the ownership the more likely it is that the firm charges the profit-maximizing price.

Introduction générale – Le logement : un bien espace-temps / Introduction – Housing: A space-time goodJournal articleAlain Trannoy, Economie et Statistique / Economics and Statistics, Issue 500-501-502, pp. 5-11, 2018

[Fr] Le logement est le bien capital dans tous les sens du terme pour les ménages, en même temps bien de consommation par le flux de services qu’il prodigue et élément constitutif essentiel du patrimoine pour les propriétaires. Capital aussi, car représentant plus qu’un quart des dépenses de consommation des ménages, une hausse des loyers ou des prix a tout de suite des répercussions très importantes sur le niveau de vie, sur les choix de localisation, sur les mobilités, sur les choix d’épargne. Le logement est capital également car il est unique comme élément d’un espace-temps, espace et temps absolument indissociables pour l’occasion. Tous ces thèmes trouvent un écho dans ce numéro spécial riche d’approches et de perspectives différentes qui apportent de précieuses informations sur nombre de questions en suspens.
[Eng] Housing is a crucial good for households, both as a consumer good via the flow of services it fosters, and as an essential component of a homeowner’s wealth. It is also crucial because it accounts for more than a quarter of household’s expenses, and an increase in rent or property prices instantly has a major impact on their living standards, choice of location, mobility, and savings options. Finally, housing is also crucial because it is unique as an element of space‑time, space and time that cannot be separated in this instance. These themes are examined in this special issue, with a variety of approaches and different perspectives, providing valuable information on a number of outstanding issues.