Contributions in Merlin

In this paper we introduce a stochastic network formation model where agents choose both actions and links. Neighbors in the network benefit from each other’s action levels through local complementarities and there exists a global interaction effect reflecting a strategic substitutability in actions. The tractability of the model allows us to provide a complete equilibrium characterization in the form of a Gibbs measure, and we show that the structural features of equilibrium networks are consistent with empirically observed networks. We then use our equilibrium characterization to show that the model can be conveniently estimated even for large networks. The policy relevance is demonstrated with examples of firm exit, mergers and acquisitions and subsidies in the context of R&D collaboration networks.

It is shown that the equilibrium in the asymmetric Tullock contest is unique for parameter values r ≤ 2. This allows proving a revenue ranking result saying that a revenue-maximizing designer capable of biasing the contest always prefers a contest technology with higher accuracy.

What tariffs would countries impose if they did not have to fear any retaliation? What would occur if there was a complete breakdown of trade policy cooperation? What would be the outcome if countries engaged in fully efficient trade negotiations? And what would happen to trade policy cooperation if the world trading system had a different institutional design? While such questions feature prominently in the theoretical trade policy literature, they have proven difficult to address empirically, because they refer to what-if scenarios for which direct empirical counterparts are hard to find. In this chapter, I introduce research which suggests overcoming this difficulty by applying quantitative models of commercial policy.

Social norms are a ubiquitous feature of social life and pervade almost every aspect of human social interaction. However, despite their importance we still have relatively little empirical knowledge about the forces that drive the formation, the maintenance and the decay of social norms. In particular, our knowledge about how norms affect behavior and how norm obedience and violations shape subsequent normative standards is quite limited. Here, we present a new method that makes norms identifiable and continuously observable and, thus, empirically measurable. We show – in the context of public goods provision – the quick emergence of a widely accepted social cooperation norm that demands high contributions but – in the absence of the punishment of free-riders – norm violations are frequent and, therefore, the initial normative consensus as well as the high cooperation demands required by the norm break down. However, when peer punishment is possible, norm violations are rare from the beginning and a strong and stable normative consensus as well as high contribution requests prevail throughout. Thus, when norm compliance is costly social norms tend to unravel unless norm violations are kept to a minimum. In addition, our results indicate that – in an environment that has previously shown to be detrimental for cooperation and welfare – the opportunity to form a social norm unambiguously causes high public good contributions and group welfare when peer-punishment is possible.

We document that U.S. employment polarization in the 1980-2008 period is largely generated by women. Female employment shares increase both at the bottom and at the top of the skill distribution, generating the typical U-shape polarization graph, while male employment shares decrease in a more similar fashion along the whole skill distribution. We show that a canonical model of skill-biased technological change augmented with a gender dimension, an endogenous market/home labor choice and a multi-sector environment accounts well for gender and overall employment polarization. The model also accounts for the absence of employment polarization during the 1960- 1980 period and broadly reproduces the different evolution of employment shares across decades during the 1980-2008 period. The faster growth of skill-biased technological change since the 1980s accounts for most of the employment polarization generated by the model.

Pregnancy conditions have been shown to matter for later economic success, but many threats to fetal development that have been identified are difficult to prevent. In this paper I study seasonal influenza, a preventable illness that comes around every year and causes strong inflammatory responses in pregnant women. Using administrative data from Denmark, I identify the effects of maternal influenza on the exposed offspring via sibling comparison, exploiting both society-wide influenza spread and information on individual mothers who suffer strong infections during pregnancy. In the short term, maternal influenza leads to a doubling of prematurity and low birth weight, by triggering premature labor among women infected in the third trimester. Following exposed offspring into young adulthood, I observe a 9% earnings reduction and a 35% increase in welfare dependence. These long-term effects are strongest for influenza infections during the second trimester and they are partly explained by a decline in educational attainment, pointing to cognitive impairment. This effect pattern suggests that maternal influenza damages the fetus through multiple mechanisms, and much of the damage may not be visible at birth. Taken together, these results provide evidence that strong infections during pregnancy are an often overlooked prenatal threat with long-term consequences.

China’s emergence as a great economic power has induced an epochal shift in patterns of world trade. Simultaneously, it has challenged much of the received empirical wisdom about how labor markets adjust to trade shocks. Alongside the heralded consumer benefits of expanded trade are substantial adjustment costs and distributional consequences. These impacts are most visible in the local labor markets in which the industries exposed to foreign competition are concentrated. Adjustment in local labor markets is remarkably slow, with wages and labor-force participation rates remaining depressed and unemployment rates remaining elevated for at least a full decade after the China trade shock commences. Exposed workers experience greater job churning and reduced lifetime income. At the national level, employment has fallen in U.S. industries more exposed to import competition, as expected, but offsetting employment gains in other industries have yet to materialize. Better understanding when and where trade is costly, and how and why it may be beneficial, are key items on the research agenda for trade and labor economists.

Poverty is often characterized not only by low and unstable income, but also by heavy debt burdens. We find that reducing barriers to saving through access to free savings accounts decreases participants' short-term debt by about 20%. In addition, participants who experience an economic shock have less need to reduce consumption, and subjective well-being improves significantly. Precautionary savings and credit therefore act as substitutes in providing self-insurance, and participants prefer borrowing less when a free formal savings account is available. Take-up patterns suggest that requests by others for participants to share their resources may be a key obstacle to saving.

We study from both a theoretical and an empirical perspective how a network of military alliances and enmities affects the intensity of a conflict. The model combines elements from network theory and from the politico-economic theory of conflict. We postulate a Tullock contest success function augmented by an externality: each group’s strength is increased by the fighting effort of its allies, and weakened by the fighting effort of its rivals. We obtain a closed form characterization of the Nash equilibrium of the fighting game, and of how the network structure affects individual and total fighting efforts. We then perform an empirical analysis using data on the Second CongoWar, a conflict that involves many groups in a complex network of informal alliances and rivalries. We es- timate the fighting externalities, and use these to infer the extent to which the conflict intensity can be reduced through (i) removing individual groups involved in the conflict; (ii) pacification policies aimed at alleviating animosity among groups.

We study the monotonicity of sender’s equilibrium strategy with respect to her type in signalling games. We use counterexamples to show that when the sender’s payoff is non-separable, the Spence-Mirrlees condition cannot rule out equilibria in which the sender uses non-monotone strategies. These equilibria can survive standard refinements as incentives are strict and the sender plays every action with positive probability. We provide sufficient conditions under which the sender’s strategy is monotone in every Nash equilibrium. Our conditions require the sender’s payoff to have strictly increasing differences between the state and the action profile and monotone with respect to each player’s action. We also identify and fully characterize a novel property on the sender’s payoff that we call increasing absolute differences over distributions, under which every pair of distributions over the receiver’s actions can be ranked endogenously. Our sufficient conditions fit into a number of applications, including advertising, warranty provision, education and job assignment, etc.