2025 Zayira Ray
Julius Silver Professor, Faculty of Arts and Science,
Professor of Economics, New York University
Research Associate, NBER
Part-Time Professor, University of Warwick
Research Fellow, CESifo
Spool Member, ThReD

Department of Economics, 
New York University,
19 West 4th Street
New York, NY 10012, U.S.A.
debraj.ray@nyu.edu, +1 (212)-998-8906.

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Oxford University Press, 2008. This book is now open-access; feel free to download a copy, and to buy the print version if you like the book.
≋ Three Randomly Selected Papers
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Ethnicity and Conflict: An Empirical Study

(with Joan Esteban and Laura. Mayoral), American Economic Review 102, 1310-1342, 2012. Online Appendix.

Summary. We examine empirically the impact of ethnic divisions on conflict, by using a specification based on Esteban and Ray (2011). That theory links conflict intensity to three indices of ethnic distribution: polarization, fractionalization, and the Gini-Greenberg index. The empirical analysis verifies that these distributional measures are significant correlates of conflict. These effects persist as we introduce country-specific measures of group cohesion and of the importance of public goods, and combine them with the distributional measures exactly as described by the theory.

Egalitarianism and Incentives

(with Kaoru Ueda), Journal of Economic Theory 71, 324-348, 1996.

Summary. A group of agents is collectively engaged in a joint productive activity. Each agent supplies an observable input, and output is then collectively shared among the members according a social welfare function. However, individual actions are taken on a selfish basis, and the collective decision is only made after inputs are chosen. This leads to inefficiency. The aim of this paper is to show formally that, contrary to popular belief, the degree of inefficiency decreases in the extent of egalitarianism embodied in the social welfare function.

The Great Gatsby Curve: Upward Mobility, Persistence and Inequality

(with Garance Genicot and Laura Mayoral). December 2025.

Summary.  This paper revisits the Great Gatsby curve that connects inequality to mobility, using panel data spanning several countries and time periods. Existing literature observes that the intergenerational elasticity of earnings is positively correlated with inequality, implying that mobility (viewed as the negative of that elasticity) decreases with inequality. In sharp contrast, we show that measures of upward mobility, axiomatically based on progressivity in income growth rates, are robustly and positively associated with baseline inequality. While there is no logical contradiction here, our study highlights crucial differences between mobility measures based on (lower) persistence and those based on growth progressivity, and asks the reader to align their choice of measure with foundational criteria that they feel best describe “mobility.” Our findings offer a re-interpretation of the Gatsby curve through the lens of shared prosperity, and have implications for the evolution of inequality within countries.