Publications

La plupart des informations présentées ci-dessous ont été récupérées via RePEc avec l'aimable autorisation de Christian Zimmermann
Modeling the impact of product quality on dynamic pricing and advertising policiesRégis 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.

Optimal Time Interval Selection in Long-Run Correlation EstimationPedro H. Albuquerque, Journal of Quantitative Economics, Forthcoming

This paper presents an asymptotically optimal time interval selection criterion for the long-run correlation block estimator (Bartlett kernel estimator) based on the Newey–West and Andrews–Monahan approaches. An alignment criterion that enhances finite-sample performance is also proposed. The procedure offers an optimal alternative to the customary practice in finance and economics of heuristically or arbitrarily choosing time intervals or lags in correlation studies. A Monte Carlo experiment using parameters derived from Dow Jones returns data confirms that the procedure can be MSE-superior to alternatives such as aggregation over arbitrary time intervals, parametric VAR, and Newey–West covariance matrix estimation with automatic lag selection.

Informal risk-sharing cooperatives: the effect of learning and other-regarding preferencesVictorien Barbet, Renaud Bourlès et Juliette Rouchier, Journal of Evolutionary Economics, Forthcoming

We study the dynamics of risk-sharing cooperatives among heterogeneous agents. Based of their knowledge on their risk exposure and the performance of the cooperatives, agents choose whether or not to remain in the risk-sharing agreement. We highlight the key role of other-regarding preference (altruism and inequality aversion) in stabilizing less segregated (and smaller) cooperatives. Limited knowledge and learning of own risk exposure also contributes to reducing segregation, the two effects (of learning and other-regarding preferences) being complementary. Our findings shed light on the mechanisms behind risk-sharing agreements between agents heterogeneous in their risk exposure.

The integration of young workers into the labour market in FranceStephen Bazen et Khalid Maman Waziri, International Journal of Manpower, Forthcoming

Purpose Using a representative survey of young persons having left full-time education in France in 1998 and interviewed in 2001 and 2005, the purpose of this paper is to examine the process of their integration into normal employment (a stable job with a standard employment contract) and the extent to which job matches are inefficient in the sense that the pay in a job is below an individual’s potential earnings. The latter are determined principally by diploma level and educational specialisation, although other forms of training and labour market experience are relevant. Design/methodology/approach A stochastic earnings frontier approach is used in order to examine workers’ ability to capture their full potential earnings in labour markets where there is inefficient job matching (due to the lack of information, discrimination, over-education or the process of integration). Findings The results suggest that young workers manage to obtain on average about 82 per cent of their potential earnings three years after leaving full-time education and earnings inefficiency had disappeared four years later. The results are robust to the treatment of selectivity arising from the exclusion of the unemployed in the estimation of the frontier. Originality/value The stochastic earnings frontier is a useful and appropriate tool for modelling the process of labour market integration of certain groups (young persons, migrants and the long-term unemployed) where over-education due to inefficient initial job matches occurs. Over time this situation tends to be rectified as job mobility leads to improved matching and less inefficiency.

Time-varying consumption tax, productive government spending, and aggregate instabilityMauro Bambi et Alain Venditti, International Journal of Economic Theory, Volume n/a, Issue n/a, Forthcoming

In this paper we investigate if government balanced-budget rules together with endogenous taxation may lead to aggregate instability in an endogenous growth framework. After highlighting the differences with the exogenous growth framework, we prove that under counter-cyclical consumption taxes, while there exists a unique balanced growth path, sunspot equilibria based on self-fulfilling expectations occur through a form of global indeterminacy. In addition, we argue that this result is empirically plausible for a large set of OECD countries and that it may also emerge with endogenous income taxes.

A theory of heterogeneous city growthChristian Ghiglino, Kazuo Nishimura et Alain Venditti, International Journal of Economic Theory, Volume n/a, Issue n/a, Forthcoming

We consider an economy with three cities producing different outputs. Two cities produce intermediate goods, a type 1 city producing an intermediate “agricultural” good with capital and labor only, and a type 2 city producing an intermediate “industrial” good with capital, labor, and human capital. A type 3 city produces the final good which is obtained from the two intermediate goods and labor. The asymmetric introduction of human capital allows us to prove that the three cities experience, at equilibrium, heterogeneous endogenous growth rates which are proportional to the growth rate of human capital. We show that the “industrial” type 2 city is characterized by the larger growth rate while the “agricultural” type 1 city experiences the lower growth rate, and thus the type 3 city is characterized by a growth rate which is a convex combination of the two former growth rates. This implies that the relative size in terms of output of the “agricultural” city decreases over time. This property allows us to recover the empirical fact that most non-agricultural production occurs in growing metropolitan areas. But, simultaneously, as we prove that total labor employed in each city is proportional to the total population, the relative population size distribution of cities is constant over time, as shown in empirical studies.

Biodiversity, Shapley value and phylogenetic trees: some remarksHubert Stahn, Journal of Mathematical Biology, Forthcoming

This paper explores the main differences between the Shapley values of a set of taxa introduced by Haake et al. (J Math Biol 56:479–497, 2007. https://doi.org/10.1007/s00285-007-0126-2) and Fuchs and Jin (J Math Biol 71:1133–1147, 2015. https://doi.org/10.1007/s00285-014-0853-0), the latter having been found identical to the Fair Proportion index (Redding and Mooers in Conserv Biol 20:1670–1678, 2006. https://doi.org/10.1111/j.1523-1739.2006.00555.x). In line with Shapley (in: Kuhn, Tucker (eds) Contributions to to the theory of games, volume II, annals of mathematics studies 28, Princeton University Press, Princeton, 1953), we identify the cooperative game basis for each of these two classes of phylogenetic games and use them (i) to construct simple formulas for these two Shapley values and (ii) to compare these different approaches. Using the set of weights of a phylogenetic tree as a parameter space, we then discuss the conditions under which these two values coincide and, if they are not the same, revisit Hartmann’s (J Math Biol 67:1163–1170, 2013. https://doi.org/10.1007/s00285-012-0585-y) convergence result. An example illustrates our main argument. Finally, we compare the species ranking induced by these two values. Considering the Kendall and the Spearman rank correlation coefficient, simulations show that these rankings are strongly correlated. These results are consistent with Wicke and Fischer (J Theor Biol 430:207–214, 2017. https://doi.org/10.1016/j.jtbi.2017.07.010), who reach similar conclusions with a different simulation method.

Marketplace or reselling? A signalling modelNada Belhadj, Didier Laussel et Joana Resende, Information Economics and Policy, Forthcoming

This paper shows that the platforms’ private information on demand may explain the empirical observation that platforms like Amazon resell high-demand products, while acting as marketplace for low-demand goods. More precisely, the paper examines the strategic interaction between a seller and a better informed platform within a signalling game. We consider that the platform may choose between two distinct business models: act as a reseller or work as a pure marketplace between the buyers and the seller. The marketplace mode, which allows to internalize the spillover between the platform’s sales and the seller’s direct sales is always preferred for a low-value good. The reselling mode, which allows the platform to take advantage of its private information, may be selected in the case of high-value goods provided that (i) the externalities between direct sales and platform sales are not too strong and (ii) the difference between consumers’ willingness to pay for the high and the low-value goods is large enough. Under these conditions, the game displays a Least-Cost Separating Equilibrium in which the platform works as a marketplace for low-demand goods, while it acts as a reseller in the case of high-demand goods.

Complementary Monopolies with asymmetric informationDidier Laussel et Joana Resende, Economic Theory, Forthcoming

We investigate how asymmetric information on final demand affects strategic interaction between a downstream monopolist and a set of upstream monopolists, who independently produce complementary inputs. We study an intrinsic private common agency game in which each supplier i independently proposes a pricing schedule contract to the assembler, specifying the supplier’s payment as a function of the assembler’s purchase of input i. We provide a necessary and sufficient equilibrium condition. A lot of equilibria satisfy this condition but there is a unique Pareto-undominated Nash equilibrium from the suppliers’ point of view. In this equilibrium, there are unavoidable efficiency losses due to excessively low sales of the good. However, suppliers may be able to limit these distortions by implicitly coordinating on an equilibrium with a rigid (positive) output in bad demand circumstances.

In the name of the father: inheritance systems and the dynamics of state capacityÈric Roca Fernández, Macroeconomic Dynamics, pp. 1-28, Forthcoming

This paper examines how the degree of gender-egalitarianism embedded in inheritance rules impacts state capacity at its early stages during medieval times. We present a theoretical model in which building state capacity enables nobles to raise taxes and overcome rivals. The model addresses the use of inheritance to consolidate landholding dynasties, also accommodating interstate marriages between landed heirs. On the one hand, dynastic continuity—of utmost importance to medieval lords—directly encourages state-building. Male-biased inheritance rules historically maximize the likelihood of dynastic continuity. We weigh this effect against the indirect impact of the more frequent land-merging marriages under gender-egalitarian rules. Contrary to the literature, our results suggest that gender-egalitarian norms—offering a low probability of dynastic continuity—promote state capacity in the short run more than gender-biased norms. In the long run, results are reversed, providing a rationale for the pervasive European tradition of preference for men as heirs.