Providing global public goods under uncertaintyJournal articleYann Bramoullé et Vincent Boucher, Journal of Public Economics, Volume 94, Issue 9-10, pp. 591-603, 2010

We study how uncertainty and risk aversion affect international agreements to supply global public goods. We consider a benchmark model with homogeneous countries and linear payoffs. When countries directly contribute to a public good, uncertainty tends to lower signatories' efforts but may increase participation. Despite risk aversion, uncertainty may improve welfare. In contrast, when countries try to reduce a global public bad, uncertainty tends to increase signatories' efforts and decrease participation. In that case, an ex-ante reduction of uncertainty may have a large positive multiplier effect on welfare.

Social networks and labor market transitionsJournal articleYann Bramoullé et Gilles Saint-Paul, Labour Economics, Volume 17, Issue 1, pp. 188-195, 2010

We study the influence of social networks on labor market transitions. We develop the first model where social ties and job status coevolve through time. Our key assumption is that the probability of formation of a new tie is greater between two employed individuals than between an employed and an unemployed individual. We show that this assumption generally generates negative duration dependence of exit rates from unemployment. Our model has a number of novel testable implications. For instance, we show that a higher connectivity among unemployed individuals reduces duration dependence and that exit rates depend positively on the duration of the last job held by the unemployed worker.

Social Networks: EconometricsBook chapterYann Bramoullé et Bernard Fortin, In: The New Palgrave Dictionary of Economics, Steven N. Durlauf et Lawrence E. Blume (Eds.), 2010, Volume 4, Palgrave Macmillan, 2010

In a social network, agents have their own reference group which may influence their behaviour. In turn, the agents' attributes and their behaviour affect the formation and the structure of the social network. This paper surveys the econometric literature on both aspects of social networks, and discusses the identification and estimation issues they raise.

Identification of peer effects through social networksJournal articleYann Bramoullé, Habiba Djebbari et Bernard Fortin, Journal of Econometrics, Volume 150, Issue 1, pp. 41-55, 2009

We provide new results regarding the identification of peer effects. We consider an extended version of the linear-in-means model where interactions are structured through a social network. We assume that correlated unobservables are either absent, or treated as network fixed effects. We provide easy-to-check necessary and sufficient conditions for identification. We show that endogenous and exogenous effects are generally identified under network interaction, although identification may fail for some particular structures. We use data from the Add Health survey to provide an empirical application of our results on the consumption of recreational services (e.g., participation in artistic, sports and social activities) by secondary school students. Monte Carlo simulations calibrated on this application provide an analysis of the effects of some crucial characteristics of a network (i.e., density, intransitivity) on the estimates of peer effects. Our approach generalizes a number of previous results due to Manski [Manski, C., 1993. Identification of endogenous social effects: The reflection problem. Review of Economic Studies 60 (3), 531-542], Moffitt [Moffitt, R., 2001. Policy interventions low-level equilibria, and social interactions. In: Durlauf, Steven, Young, Peyton (Eds.), Social Dynamics. MIT Press] and Lee [Lee, L.F., 2007. Identification and estimation of econometric models with group interactions, contextual factors and fixed effects. Journal of Econometrics 140 (2), 333-374]. © 2009 Elsevier B.V. All rights reserved.

Can Uncertainty Alleviate the Commons Problem?Journal articleYann Bramoullé et Nicolas Treich, Journal of the European Economic Association, Volume 7, Issue 5, pp. 1042-1067, 2009

Global commons problems, such as climate change, are often affected by severe uncertainty. The paper examines the effect of uncertainty on pollution emissions and welfare in a strategic context. We find that emissions are always lower under uncertainty than under certainty, reflecting risk-reducing considerations. We show that uncertainty can have a net positive impact on the welfare of risk-averse polluters. We extend the analysis to increases in risk, increases in risk-aversion, and to risk heterogeneity. (JEL: D81, C72, Q54, H23) (c) 2009 by the European Economic Association.

Risk Sharing Across CommunitiesJournal articleYann Bramoullé et Rachel Kranton, American Economic Review, Volume 97, Issue 2, pp. 70-74, 2007

No abstract is available for this item.

Public goods in networksJournal articleYann Bramoullé et Rachel Kranton, Journal of Economic Theory, Volume 135, Issue 1, pp. 478-494, 2007

No abstract is available for this item.

Anti-coordination and social interactionsJournal articleYann Bramoullé, Games and Economic Behavior, Volume 58, Issue 1, pp. 30-49, 2007

No abstract is available for this item.

Risk-sharing networksJournal articleYann Bramoullé et Rachel Kranton, Journal of Economic Behavior & Organization, Volume 64, Issue 3-4, pp. 275-294, 2007

This paper considers the formation of risk-sharing networks. Following empirical findings, we build a model where pairs form links, but a population cannot coordinate links. As a benchmark, individuals commit to share monetary holdings equally with linked partners. We find efficient networks can (indirectly) connect all individuals and involve full insurance. But equilibrium networks connect fewer individuals. When breaking links, individuals do not consider negative externalities on others in the network. Thus identical individuals can end up in different positions in a network and have different outcomes. These results may help to explain empirical findings that risk-sharing is often asymmetric.

Allocation of pollution abatement under learning by doingJournal articleYann Bramoullé et Lars J. Olson, Journal of Public Economics, Volume 89, Issue 9-10, pp. 1935-1960, 2005

No abstract is available for this item.