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International audience; We consider the link between poverty and subjective wellbeing and focus in particular on potential adaptation to poverty. We use panel data on almost 54,000 individuals living in Germany from 1985 to 2012 to show, first, that life satisfaction falls with both the incidence and intensity of contemporaneous poverty. We then reveal that there is little evidence of adaptation within a poverty spell: poverty starts bad and stays bad in terms of subjective well-being. We cannot identify any cause of poverty entry that explains the overall lack of poverty adaptation.

We introduce a ranking of multidimensional alternatives, including un- certain prospects as a particular case, when these objects can be given a matrix form. This ranking is separable in terms of rows and columns, and continuous and monotonic in the basic quantities. Owing to the theory of additive separability developed here, we derive very precise numerical representations over a large class of domains (i.e., typically not of the Cartesian product form). We apply these representation to (1) streams of commodity baskets through time, (2) uncertain social prospects, (3) un- certain individual prospects. Concerning (1), we propose a finite horizon variant of Koopmans's (1960) axiomatization of infinite discounted util- ity sums. The main results concern (2). We push the classic comparison between the ex ante and ex post social welfare criteria one step further by avoiding any expected utility assumptions, and as a consequence ob- tain what appears to be the strongest existing form of Harsanyi's (1955) Aggregation Theorem. Concerning (3), we derive a subjective probability for Anscombe and Aumann's (1963) finite case by merely assuming that there are two epistemically independent sources of uncertainty. characteristics.

International audience; We address in this paper the question of the existence of a Social Welfare Function that would be sustainable and would allow us to obtain solutions to optimal growth models. We define sustainability by two new axioms called Never-decisiveness of the present and Never-decisiveness of the future. We first show that a SWF which has Never-decisiveness properties cannot be defined on a ball of l+∞. We must (i) restrict to the set of utility streams for which the value of the SWF is finite and (ii) introduce additional assumptions in order to obtain the Never-decisiveness properties. Our main result in this paper is therefore to show that the undiscounted utilitarian criterion is an anonymous and never-decisive criterion for optimal growth models. We consider the set of utilities of consumptions which are generated by a specific technology, namely a technology with decreasing returns for high levels of capital, and restrict ourselves to good programs, i.e., any program for which intertemporal utility is well defined.

Quantifications of gains from trade in heterogeneous firm models assume that productivity is Pareto distributed. Replacing this assumption with log-normal heterogeneity retains some useful Pareto features, while providing a substantially better fit to sales distributions-especially in the left tail. The cost of log-normal is that gains from trade depend on the method of calibrating the fixed cost and productivity distribution parameters. When set to match the size distribution of firm sales in a given market, the log-normal assumption delivers gains from trade in a symmetric two-country model that can be twice as large as under the Pareto assumption.

We consider the link between poverty and subjective well-being, and focus in particular on the role of time. We use panel data on 42,500 individuals living in Germany from 1992 to 2010 to uncover four empirical relationships. First, life satisfaction falls with both the incidence and intensity of contemporaneous poverty. There is no evidence of adaptation within a poverty spell: poverty starts bad and stays bad in terms of subjective well-being. Third, poverty scars: those who have been poor in the past report lower life satisfaction today, even when out of poverty. Last, the order of poverty spells matters: for a given number of poverty spells, satisfaction is lower when the spells are concatenated: poverty persistence reduces well-being. These effects differ by population subgroups.

As people are spending more time online, it is important to evaluate the impact of Internet use on individual well-being. Internet use yields direct utility and economic returns (e.g. better job, higher productivity) that may increase life sa-tisfaction. But the Internet might also have detrimental effects (addiction, social isolation, e.g.). This paper empirically examines the relation between Internet use and subjective well-being. Using Luxemburgish data from a European so-cial survey, we find evidence that non users are less satisfied in their life than Internet users. This result holds when we control for socio-demographic charac-teristics, social capital, values and beliefs, and health and income. Moreover, the positive influence of Internet use is stronger for low income and young in-dividuals. These findings suggest that public policy aiming to reduce the digital divide are socially desirable..

L'économie du bien-être ou welfarisme, qui pose que les seules informations pertinentes pour juger les états sociaux sont les utilités individuelles (Sen, 1979), a très longtemps occupé une place hégémonique dans le champ de l'économie normative. Le modèle ELIE de redistribution des revenus (ELIE signifiant Equal-Labour Income Equalization) se présente, de manière à la fois très explicite et récurrente, comme rompant avec cette tradition aujourd'hui encore dominante (Kolm, 2005, 2011b). Ce papier interroge le sens de cette prise de distance avec le welfarisme. Après avoir procédé à un certain nombre de mises au point concernant, d'une part, le modèle ELIE et, d'autre part, le welfarisme, nous discutons les différents aspects de la rupture du modèle ELIE de redistribution des revenus avec le welfarisme.

Limited consumer attention limits product market competition: prices are stochastically lower the more attention is paid. Ads compete to be the lowest price with other ads from the same sector and they compete for attention with ads from other sectors: equilibrium sector ad shares under free entry follow a CES form. When a sector gets more attractive, its advertising expands: others lose ad market share but may increase in absolute terms if sufficiently attractive. The "information hump" shows highest ad levels for intermediate attention levels when there is a decent enough chance of getting the message across and also of not being undercut by a cheaper offer. The Information Age takes off when the number of sectors grows, but total ad volume reaches an upper limit. Overall, advertising is excessive, though the allocation across sectors is optimal. Nonetheless, both large sectors and small ones can be blamed for misallocation of ads in using up scarce attention.

This paper explores the possible impact of the combination of forest and non-forest settings on recreation values. We extend the traditional contingent valuation method by introducing seven dichotomous choice occasions. To answer each valuation question, each respondent is asked to choose between a policy scheme and the status quo. Each scheme is composed of various programmes while each programme is linked to the recreational quality of one natural area. An extra distance is used as a proxy of the bid. The results show that respondents distinguish between schemes according to the number of programmes included. Nevertheless, a “ substitution effect” occurs when all programmes are supposed to be implemented. Individual WTP ranges from € 6.51 for the forest alone (e. g. 55.35 extra kilometres per group-vehicle) to € 18.11 (e. g. 153.9 extra kilometres per group-vehicle) for the complete scheme. Our results stress the fact that recreation in forests must not be isolated from other natural areas. From a more general point of view, valuation based on multi-attribute approaches must be favoured on “ multi-environment” sites., La fréquentation touristique des forêts littorales : la forêt a-t-elle une influence ? Cet article étudie l’impact de la combinaison d’espaces forestiers et non forestiers sur la valeur économique d’un site récréatif. Nous utilisons une extension de la méthode d’évaluation contingente visant à présenter sept occasions de choix dichotomiques. Lors de ces questions d’évaluation, chaque enquêté est invité à choisir entre une politique d’amélioration de la qualité du site et la situation de référence. Les politiques se composent de plusieurs programmes et chacun de ces derniers est lié à la qualité récréative d''un espace naturel. Les résultats montrent que les personnes interrogées différencient les politiques selon le nombre de programmes qu’elles comportent. Néanmoins, un effet de «substitution » se produit lorsque tous les programmes sont mis en oeuvre. Les consentements à payer individuels s’échelonnent de 6,51 € (ou 55,35 kilomètres par groupe-véhicule) lorsque seule la forêt est visée à 18,11 € (ou 153,9 kilomètres par groupe-véhicule) lorsque la totalité des espaces présents profite de l’amélioration. Nos résultats soulignent la nécessité de replacer les forêts dans leur environnement immédiat et, plus généralement, l’intérêt d’utiliser des approches multi-attributs pour estimer la valeur économique de sites récréatifs aux environnements variés., Rulleau Bénédicte, Dehez Jeoffrey, Point Patrick. The tourist recreational demand for coastal forests: Do forests really matter?. In: Revue d’études en Agriculture et Environnement, Vol. 92, N°3, 2011. pp. 291-310.

Economic studies that aim at comparing the patent system social efficiency versus an ex-post reward system rest on a traditional view of patents. They make the hypothesis that firms use the patent system only in order to be granted a short-term monopoly rent and therefore that patents lead to strong and steady monopolies. This assumption is convenient because it allows straightforward comparisons between patent and reward systems. But empirical studies do not confirm this vision of patents. Most firms do not consider patents as efficient devices to exploit commercial monopoly positions. Patents are rather perceived as strategic devices to signal firms’ competences and to strengthen firms’ bargaining power during negotiations prior to knowledge exchange and to R&D cooperation. These changes lead to rethink the framework of the patent-reward debate.

International audience; The paper analyses economic evaluations by distinguishing evaluative statements from actual value judgments. From this basis, it compares four solutions to the value neutrality problem in economics. After rebutting the strong theses about neutrality (normative economics is illegitimate) and non-neutrality (the social sciences are value-impregnated), the paper settles the case between the weak neutrality thesis (common in welfare economics) and a novel, weak non-neutrality thesis that extends the realm of normative economics more widely than the other weak thesis does.

Cahier de Recherche du Groupe HEC Paris, n° 694; When the asset market is incomplete, competitive equilibria are constrained suboptimal, which provides a scope for pareto improving interventions. Price regulation can be such a pareto improving policy, even when the welfare effects of rationing are taken into account. An appealing aspect of price regulation is that it that it operates anonymously on market variables. Fix - price equilibria exist under weak assumptions. Such equilibria permit a competitive analysis of an economy with an incomplete asset market that is out of equilibrium. Arbitrage opportunities may arise: with three or more assets actively traded, an individual may hold an arbitrage portfolio at equilibrium. The local existence of fix- price equilibrium for prices that are almost competitive may fail for robust examples. Under necessary and sufficient conditions for the local existence of fix - price equilibria, pareto improving price regulation is generically possible.

This paper analyses the impact of multiple competitive equilibria and complete markets in a simple general equilibrium model. A random selection from the equilibrium correspondence of a finite exchange economy defines probability distributions on equilibrium prices. Asset markets allow traders to insure against the resulting uncertainty. If asset markets are complete, equilibrium selections are necessarily degenerate. The selection cannot be non- trivially random, and must assign probability one to particular equilibrium price vectors. In this case, asset prices reveal the choice of equilibrium price vectors and achieve the coordination of traders' expectations. If the asset market is incomplete, equilibrium selections can be non-degenerate, so that price uncertainty is self-fulfilling. A fully insured random selection defines an iterative procedure of reallocations which is Pareto improving at each step. The process converges to a Pareto optimum in finitely many steps. The key requirement is that the random selection be continuous, which is a generic condition for smooth exchange economies with strictly concave utility functions.