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


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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On the Competitive Pressure Induced by the Diffusion of Innovations

(with Dilip Mookherjee), Journal of Economic Theory 54, 124-147, 1991.

Summary. We consider the decision of a dominant firm to adopt a sequence of potential cost-reducing innovations, where the latest technology adopted diffuses to a competitive fringe at an exogenous rate. With price competition on the product market, the leader optimally spaces apart the adoption dates of successive innovations, so the industry is characterized by cycles of alternating innovation and diffusion. These results may, however, be reversed in the case of quantity competition.

Contracts with Interdependent Preferences

(with Marek Weretka), February 2025.

Summary.  A principal contracts with a team of agents with interdependent preferences. We characterize cost effective contracts, and relate the direction of co-movement in rewards — “joint liability” (positive) or “tournaments” (negative) — to the assumed structure of preference interdependence.  We identify two asymmetries. First, the optimal contract leans towards joint liability rather than tournaments, especially in larger teams, in a sense made precise in the paper. Second, when the mechanism-design problem is augmented by robustness constraints designed to eliminate multiple equilibria, the principal may prefer teams linked via adversarial rather than altruistic preferences.

Decoding India’s Low Covid-19 Case Fatality Rate

(with Minu Philip and S. Subramanian),  Journal of Human Development and Capabilities 22, 27-51 (2021).

Summary. India’s case fatality rate (CFR) under covid-19 is strikingly low, trending from 3% or more, to a current level of under 1.8%. The world average rate is far higher. Several observers have noted that this difference is at least partly due to India’s younger age distribution. In this paper, we use age-specific fatality rates from comparison countries, coupled with India’s distribution of covid-19 cases to “predict” what India’s CFR would be with those age-specific rates. In most cases, those predictions are lower than India’s actual performance, suggesting that India’s CFR is, if anything, too high rather than too low.