Macroeconomics

We study economies of asymmetric information with observable types. Trade takes place in lotteries. Individuals face a standard budget constraint, while the incentive compatibility constraints are imposed on the production set of the intermediaries. This formalization encompasses moral hazard and private information economies. Equilibrium allocations are constrained efficient, but, contrary to what stated for example in Jerez (2005), the set of equilibrium allocations may be empty and the Second Welfare Theorem may fail. This happens for two reasons.

Price momentum strategies have historically generated high positive returns with little systematic risk. However, these strategies also experience infrequent but severe losses. During 13 of the 978 months in our 1929–2010 sample, losses to a US-equity momentum strategy exceed 20 percent per month. We demonstrate that a hidden Markov model in which the market moves between latent "turbulent" and "calm" states in a systematic stochastic manner captures these high-loss episodes.

We investigate whether progress towards an international treaty on greenhouse gas emissions could benefit from insights about tipping a non-cooperative game from an inefficient to an efficient equilibrium. Games with increasing differences have multiple equilibria and have a “tipping set,” a subset of agents who by changing from the inefficient to the efficient equilibrium can induce all others to do the same. We argue that international climate negotiations form such a game and so have a tipping set. This can provide a novel perspective on finding a way forward in climate negotiations.

We develop a dynamic theory of resource wars and study the conditions under which such wars can be prevented. Our focus is on the interaction between the scarcity of resources and the incentives for war in the presence of limited commitment. We show that a key parameter determining the incentives for war is the elasticity of demand. Our first result identifies a novel externality that can precipitate war: price-taking firms fail to internalize the impact of their extraction on military action.

Using accounting data for 7722 non-financial firms in 42 countries, we examine how the 2007–2009 crisis affected firm performance and how various linkages propagated shocks across borders. We isolate and compare effects from changes in business cycle, international trade, and external financing conditions, on firms' profits, sales and investment using both sectoral benchmarks and firm-specific sensitivities estimated prior to the crisis.

This article characterizes optimal policy when a government uses indirect control toexert its authority. Wedevelopadynamicprincipal-agent model inwhich a principal (a government) delegates thepreventionof a disturbance–suchas riots, protests, terrorism, crime, or tax evasion–to an agent who has an advantage in accomplishing this task. Our setting is a standard repeated moral hazard model with two additional features. First, the principal is allowed to exert direct control by intervening with an endogenously determined intensity of force which is costly to both players.

Are teachers' impacts on students' test scores ("value-added") a good measure of their quality? This question has sparked debate largely because of disagreement about (1) whether value-added (VA) provides unbiased estimates of teachers' impacts on student achievement and (2) whether high-VA teachers improve students' long-term outcomes. We address these two issues by analyzing school district data from grades 3–8 for 2.5 million children linked to tax records on parent characteristics and adult outcomes.

While the high savings rate in China has global impact, existing explanations are incomplete. This paper proposes a competitive saving motive as a new explanation: as the country experiences a rising sex ratio imbalance, the increased competition in the marriage market has induced the Chinese, especially parents with a son, to postpone consumption in favor of wealth accumulation. The pressure on savings spills over to other households through higher costs of house purchases. Both cross-regional and household-level evidence supports this hypothesis.

Economic evaluation of climate policy traditionally treats uncertainty by appealing to expected utility theory. Yet our knowledge of the impacts of climate policy may not be of sufficient quality to justify probabilistic beliefs. In such circumstances, it has been argued that the axioms of expected utility theory may not be the correct standard of rationality. By contrast, several axiomatic frameworks have recently been proposed that account for ambiguous beliefs. In this paper, we apply static and dynamic versions of a smooth ambiguity model to climate mitigation policy.