Contributions in Merlin

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.

This paper documents how saving constraints can spill over into other markets. When producers value saving devices, trustworthy buyers can offer them infrequent payments—a commitment tool—and purchase at a lower price. This affects the nature of competition in the output market. We present a model of this interlinked saving-output market for the case of the Kenyan dairy industry. Multiple data sources, experiments, and a calibration exercise support its microfoundations and predictions concerning: i) producers’ demand for infrequent payments; ii) an asymmetry across buyers in the ability to credibly commit to low frequency payments; iii) a segmented market equilibrium where buyers compete by providing either liquidity or saving services to producers; iv) low supply response to price increases. We discuss additional evidence from other contexts, including labor markets, and derive policy implications concerning contract enforcement, financial access, and market structure.

In this paper we use cross-state panel data to show that top income inequality is (at least partly) driven by innovation. We first establish a positive and significant correlation between various measures of innovativeness and top income inequality in cross-state panel regressions. Two distinct instrumentation strategies suggest that this correlation (partly) reflects a causality from innovativeness to top income inequality, and the effect is significant: for example, when measured by the number of patent per capita, innovativeness accounts on average across US states for around 17% of the total increase in the top 1% income share between 1975 and 2010. Finally, we show that innovation does not increase broader measures of inequality which do not focus on top incomes, and that innovation is positively correlated with social mobility, but less so in states with more intense lobbying activities.

Do contractual frictions matter when firms are engaged in repeated interactions? This paper argues that long-term relationships, which allow firms to (partly) overcome the static costs associated with low contractibility, will under certain circumstances create dynamic inefficiencies. We consider the repeated interaction between final good producers and intermediate input suppliers, where the provision of the intermediate input is noncontractible. A producer/supplier pair can be a good match or a bad match, with bad matches featuring lower productivity. This allows us to build a cooperative equilibrium where producers can switch suppliers and start cooperation immediately with new suppliers. Every period, one supplier has the opportunity to innovate, and in the baseline model, innovations are imitated after one period. We show that (i) innovations need to be larger to break up existing relationships in the cooperative equilibrium than in either a set-up where the input is contractible or when we preclude cooperation in long-term relationships, (ii) the rate of innovation in the cooperative equilibrium is lower than in the contractible case, and may even be lower than in the non-cooperative equilibrium and (iii) cooperation may reduce welfare. Next, we assume that the frontier technology diffuses slowly to suppliers (instead of after one period). In that case, for sufficiently slow diffusion, the innovation rate in the cooperative equilibrium may be higher than even in the contractible case. Finally, we show that cooperation may also increase relationship specific innovations.

Reducing tax evasion is a key priority for many governments, particularly in developing countries. A growing literature has argued that the ability to verify taxpayer self-reports against reports from third parties is critical for modern tax enforcement and the growth of state capacity. However, there may be limits to the effectiveness of third-party information if taxpayers can make offsetting adjustments on less verifiable margins. We present a simple framework to demonstrate the conditions under which this will occur and provide strong empirical evidence for such behavior by exploiting a natural experiment in Ecuador. We find that when firms are notified by the tax authority about detected revenue discrepancies on previously filed corporate income tax returns, they increase reported revenues, matching the third-party estimate when provided. Firms also increase reported costs by 96 cents for every dollar of revenue adjustment, resulting in minor increases in total tax collection.

We develop a tractable dynamicmodel of productivity growth and technology spillovers that is consistent with the emergence of real world empirical productivity distributions. Firms can improve productivity by engaging in in-house R&D, or alternatively, by trying to imitate other firms’ technologies, subject to the limits of their absorptive capacities. The outcome of both strategies is stochastic. The choice between in-house R&Dand imitation is endogenous, and based on firms’ profit maximization motive. Firms closer to the technological frontier face fewer imitation opportunities, and choose in-house R&D, while firms farther from the frontier try to imitate more productive technologies. The equilibriumchoice leads to a balanced-growth equilibriumfeaturing persistent productivity differences even when starting from ex-ante identical firms. The long-run productivity distribution can be described as a traveling wave with tails following a Pareto as can be observed in the empirical data.

We study the anticompetitive effects of predatory pricing and the efficacy of three policy responses. In a series of experiments where an incumbent and a potential entrant interact, we compare prices, market structures and welfare. Under a laissez-faire regime, the threat of post-entry price cuts discourages entry, and allows incumbents to charge monopoly prices. Current U.S. policy (Brooke Group) does not help. A policy suggested by Baumol (1979) lowers post-exit prices, while Edlin’s (2002) proposal reduces pre-entry prices and encourages entry. While both policies show outcomes after entry that are less competitive than under Laissez-Faire, they nevertheless increase consumer welfare.

We develop a unifying framework for optimal income taxation in multi-activity economies with general production technologies. Agents are characterized by an N-dimensional skill vector that captures intrinsic abilities in N activities. The private return to each activity depends on individual skill and an aggregate activity-specific return, which is a general function of the economy-wide distribution of efforts across activities. The optimal tax schedule features a multiplicative income-specific correction to an otherwise standard tax formula. Because taxes affect the relative returns to different activities, this correction diverges, in general, from the weighted average of the Pigouvian taxes that would align private and social returns in each activity. We characterize this divergence as a function of relative return elasticities, and its implications for the shape of the income tax both generally and in a number of applications, including externality-free economies with general equilibrium effects, economies with increasing or decreasing returns to scale, zero-sum activities such as bargaining or rent extraction, and positive or negative spillovers.

Mortality is a crucial dimension of wellbeing and inequality in a population, and mortality trends have been at the core of public debates in many Western countries. In this paper, we provide the first analysis of mortality inequality in Canada and compare its development to trends in the U.S. We find strong reductions in mortality rates across both genders and at all ages, with the exception of middle ages which only experienced moderate improvements. Inequality in mortality, measured across Canadian Census Divisions, decreased for infants and small children, while it increased slightly at higher ages. In comparison to the U.S., mortality levels in Canada improved at a similar rate despite lower initial levels. Inequality at younger ges, however, fell more strongly in the U.S., implying converging mortality gradients between the two countries.