A Fast Literature Search Engine based on top-quality journals, by Dr. Mingze Gao.

• Almunia, M., Lopez-Rodriguez, D., Morales, E., & s, P. A. (2021). Venting Out: Exports during a Domestic Slump. American Economic Review, 111, 3611–3662.

  We study the relationship between domestic-demand shocks and exports using data for Spanish manufacturing firms in 2002–2013. Exploiting plausibly exogenous geographical variation caused by the Great Recession, we find that firms whose domestic sales declined by more experienced a larger increase in export flows, controlling for firms' supply determinants. This result illustrates the capacity of export markets to counteract the negative impact of local demand shocks. By structurally estimating a heterogeneous-firm model of exporting with nonconstant marginal costs of production, we conclude that these firm-level responses accounted for half of the spectacular increase in Spanish goods exports over the period 2009–2013.

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• Banerjee, A., Breza, E., Chandrasekhar, A. G., & Mobius, M. (2021). Naïve Learning with Uninformed Agents. American Economic Review, 111, 3540–3574.

  The DeGroot model has emerged as a credible alternative to the standard Bayesian model for studying learning on networks, offering a natural way to model naïve learning in a complex setting. One unattractive aspect of this model is the assumption that the process starts with every node in the network having a signal. We study a natural extension of the DeGroot model that can deal with sparse initial signals. We show that an agent's social influence in this generalized DeGroot model is essentially proportional to the degree-weighted share of uninformed nodes who will hear about an event for the first time via this agent. This characterization result then allows us to relate network geometry to information aggregation. We show information aggregation preserves "wisdom" in the sense that initial signals are weighed approximately equally in a model of network formation that captures the sparsity, clustering, and small-world properties of real-world networks. We also identify an example of a network structure where essentially only the signal of a single agent is aggregated, which helps us pinpoint a condition on the network structure necessary for almost full aggregation. Simulating the modeled learning process on a set of real-world networks, we find that there is on average 22.4 percent information loss in these networks. We also explore how correlation in the location of seeds can exacerbate aggregation failure. Simulations with real-world network data show that with clustered seeding, information loss climbs to 34.4 percent.

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• Biais, B., Hombert, J., & Weill, P.-O. (2021). Incentive Constrained Risk Sharing, Segmentation, and Asset Pricing. American Economic Review, 111, 3575–3610.

  Incentive problems make securities' payoffs imperfectly pledgeable, limiting agents' ability to issue liabilities. We analyze the equilibrium consequences of such endogenous incompleteness in a dynamic exchange economy. Because markets are endogenously incomplete, agents have different intertemporal marginal rates of substitution, so that they value assets differently. Consequently, agents hold different portfolios. This leads to endogenous markets segmentation, which we characterize with optimal transport methods. Moreover, there is a basis going always in the same direction: the price of a security is lower than that of replicating portfolios of long positions. Finally, equilibrium expected returns are concave in factor loadings.

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• Bourreau, M., Sun, Y., & Verboven, F. (2021). Market Entry, Fighting Brands, and Tacit Collusion: Evidence from the French Mobile Telecommunications Market. American Economic Review, 111, 3459–3499.

  We study a major new entry in the French mobile telecommunications market, followed by the introduction of fighting brands by the three incumbents. Using an empirical oligopoly model, we find that the incumbents' fighting brand strategies are difficult to rationalize as unilateral best responses. Instead, their strategies are consistent with a breakdown of tacit semi-collusion: before entry, the incumbents could successfully coordinate on restricting product variety to avoid cannibalization; after entry, this outcome became harder to sustain because of increased business stealing incentives. Consumers gained considerably from the added variety and, to a lesser extent, from the incumbents' price responses.

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• Echenique, F., Miralles, A., & Zhang, J. (2021). Constrained Pseudo-Market Equilibrium. American Economic Review, 111, 3699–3732.

  We propose a pseudo-market solution to resource allocation problems subject to constraints. Our treatment of constraints is general: including bihierarchical constraints due to considerations of diversity in school choice, or scheduling in course allocation; and other forms of constraints needed to model, for example, the market for roommates, combinatorial assignment problems, and knapsack constraints. Constraints give rise to pecuniary externalities, which are internalized via prices. Agents pay to the extent that their purchases affect the value the of relevant constraints at equilibrium prices. The result is a constrained-efficient market-equilibrium outcome. The outcome is fair to the extent that constraints treat agents symmetrically.

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• Kostøl, A. R., & Myhre, A. S. (2021). Labor Supply Responses to Learning the Tax and Benefit Schedule. American Economic Review, 111, 3733–3766.

  Despite the implications for policy, empirical evidence on the relative importance of factors that shape labor supply responses is missing. This paper helps fill this gap and quantifies the role of information frictions versus other frictions by combining notches in the Norwegian welfare system and quasi-experimental variation in access to information about the slope and location of kinks. While we estimate a frictionless elasticity of 0.3, overall frictions attenuate this elasticity by about 70 percent. We find the information letter increased the earnings elasticity from 0.06 to 0.15, implying that information frictions account for at least 30 percent of total attenuation.

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• Madarász, K. (2021). Bargaining under the Illusion of Transparency. American Economic Review, 111, 3500–3539.

  This paper studies bargaining with noncommon priors where the buyer projects and exaggerates the probability that her private information may leak to the seller. Letting the buyer name her price first, raises the seller's payoff above his payoff from posting a price. In seller-offer bargaining, projection implies a partial reversal of classic Coasian comparative static results. Weakening price commitment can benefit the seller and, as long as the relative speed at which imaginary information versus offers arrive does not converge to zero too quickly, frictionless bargaining converges to a fast haggling process which allows the seller to extract all surplus from trade. Bargaining under common prior transparency is instead slow and becomes equivalent to simply waiting. The comparative static predictions are consistent with experimental evidence.

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• Mogstad, M., Torgovitsky, A., & Walters, C. R. (2021). The Causal Interpretation of Two-Stage Least Squares with Multiple Instrumental Variables. American Economic Review, 111, 3663–3698.

  Empirical researchers often combine multiple instrumental variables (IVs) for a single treatment using two-stage least squares (2SLS). When treatment effects are heterogeneous, a common justification for including multiple IVs is that the 2SLS estimand can be given a causal interpretation as a positively weighted average of local average treatment effects (LATEs). This justification requires the well-known monotonicity condition. However, we show that with more than one instrument, this condition can only be satisfied if choice behavior is effectively homogeneous. Based on this finding, we consider the use of multiple IVs under a weaker, partial monotonicity condition. We characterize empirically verifiable sufficient and necessary conditions for the 2SLS estimand to be a positively weighted average of LATEs under partial monotonicity. We apply these results to an empirical analysis of the returns to college with multiple instruments. We show that the standard monotonicity condition is at odds with the data. Nevertheless, our empirical checks reveal that the 2SLS estimate retains a causal interpretation as a positively weighted average of the effects of college attendance among complier groups.

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• Breza, E., Kaur, S., & Shamdasani, Y. (2021). Labor Rationing. American Economic Review, 111, 3184–3224.

  This paper measures excess labor supply in equilibrium. We induce hiring shocks—which employ 24 percent of the labor force in external month-long jobs—in Indian local labor markets. In peak months, wages increase instantaneously and local aggregate employment declines. In lean months, consistent with severe labor rationing, wages and aggregate employment are unchanged, with positive employment spillovers on remaining workers, indicating that over a quarter of labor supply is rationed. At least 24 percent of lean self-employment among casual workers occurs because they cannot find jobs. Consequently, traditional survey approaches mismeasure labor market slack. Rationing has broad implications for labor market analysis.

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• Card, D., Gerard, F., Lagos, L., & Severnini, E. (2021). Assortative Matching or Exclusionary Hiring? The Impact of Employment and Pay Policies on Racial Wage Differences in Brazil. American Economic Review, 111, 3418–3457.

  We measure the effects of firm policies on racial pay differences in Brazil. Non-Whites are less likely to be hired by high-wage firms, explaining about 20 percent of the racial wage gap for both genders. Firm-specific pay premiums for non-Whites are also compressed relative to Whites, contributing another 5 percent for that gap. A counterfactual analysis reveals that about two-thirds of the underrepresentation of non-Whites at higher-wage firms is explained by race-neutral skill-based sorting. Non-skill-based sorting and differential wage setting are largest for college-educated workers, suggesting that the allocative costs of discriminatory hiring and pay policies may be relatively large in Brazil.

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