Home Media Research Seminar Teaching Vita Voucher


For copies of papers please follow links below, see Google Scholar, or E-mail david.ridley((at))duke.edu

I am interested in innovation, location, and pricing, especially in health care.


In 2006 we proposed a priority review voucher (Ridley et al. 2006) to encourage innovation for neglected diseases. We worked with members of the Senate for passage of the voucher law in 2007. As of 2016, 11 vouchers had been awarded and 5 had been sold for an average price of around $200 million. You can read more about the priority review voucher on Wikipedia or on my voucher page. In the papers referenced below, we wrote about the voucher program and other incentives for drug development.

  1. David B. Ridley and Stephane A. Régnier. 2016. "The Commercial Market for Priority Review Vouchers." Health Affairs, 35(5): 776-783.
  2. David B. Ridley, Jennifer Dent, and Christopher Egerton-Warburton. 2016. "Efficacy of the Priority Review Voucher Program." Journal of the American Medical Association, 315(15): 1659-1660.
  3. Joshua S. Gans and David B. Ridley. 2013. "Innovation Incentives under Transferable Fast-Track Regulatory Review." Journal of Industrial Economics. Vol. 61, No. 3: 789-816. (Working paper)
  4. David B. Ridley and Alfonso Calles Sanchez. 2010. "Introduction of European Priority Review Vouchers to Encourage Development of New Medicines for Neglected Diseases." The Lancet. Vol. 376, No. 9744: 922-927. (Working paper)
  5. Jeffrey L. Moe, Henry G. Grabowski, and David B. Ridley. 2009. "FDA Review Vouchers." The New England Journal of Medicine. Vol. 360, No. 8: 837-838.
  6. David B. Ridley, Henry G. Grabowski, and Jeffrey L. Moe. 2006. "Developing Drugs for Developing Countries." Health Affairs. Vol. 25, No. 2: 313-324. Appendix (Working paper)


How does government price regulation and reimbursement affect shortages and inflation? How sensitive is demand to copayments and advertising? How does competition affect drug prices? How can we encourage lower prices for people in poor countries?

  1. Ali Yurukoglu, Eli Liebman, David B. Ridley. 2017. "The Role of Government Reimbursement in Drug Shortages." American Economic Journal: Economic Policy, 9(2): 348–382. (Working paper)
  2. David B. Ridley and Su Zhang. 2017. "Regulation of Price Increases." International Journal of Industrial Organization, 50: 186–213. (Working paper)
  3. David B. Ridley, Xiaoshu Bei, and Eli Liebman. 2016. "No Shot: US Vaccine Prices and Shortages." Health Affairs, 35(2): 235-241. (Working paper)
  4. Stephane A. Régnier and David B. Ridley. "Forecasting Market Share in the US Pharmaceutical Market." Nature Reviews Drug Discovery. 2015. Vol. 14, No. 9: 594-595. Supplement. (Working paper)
  5. David B. Ridley. "Payments, Promotion, and the Purple Pill." Health Economics. 2015. Vol. 24, No. 1: 86-103. (Working paper)
  6. Peter Arcidiacono, Paul Ellickson, Peter Landry, and David B. Ridley. "Pharmaceutical Followers." International Journal of Industrial Organization. 2013. Vol. 31, No. 5: 538–553 (NBER working paper)
    Paul Geroski Award for one of the two best papers in the journal that year.
  7. Margaret K. Kyle and David B. Ridley. "Would Greater Transparency and Uniformity of Health Care Prices Benefit Poor Patients?" Health Affairs. 2007. Vol. 26, No. 5: 1384-1391. (Working paper)
  8. Henry G. Grabowski, David B. Ridley, and Kevin A. Schulman. "Entry and Competition in Generic Biologics." Managerial and Decision Economics. 2007. Vol. 28: 439-451. (Working paper)
  9. David B. Ridley and Kirsten Axelsen. "Impact of Medicaid Preferred Drug Lists on Therapeutic Adherence." Pharmacoeconomics. 2006. Vol. 24, Suppl. 3: 65-78.


When firms cluster, they engage in more intense price competition. So why cluster? Followers cluster near leaders to i) free ride on the demand information of the market leader, ii) because they can differentiate their products and mitigate price competition, and iii) because zoning forces clustering.

  1. David B. Ridley. "Hotelling's Law." In D. Teece and M. Augier, eds. The Palgrave Encyclopedia of Strategic Management. 2013. (Working paper)
  2. David B. Ridley, Frank A. Sloan, and Yan Song. "Retail Zoning and Competition."
  3. Gabriel A. Picone, David B. Ridley, and Paul A. Zandbergen. "Distance Decreases with Differentiation: Strategic Agglomeration by Retailers." International Journal of Industrial Organization. 2009. Vol. 27, No. 3: 463-473. (Working paper)
  4. David B. Ridley. "Herding versus Hotelling: Market Entry with Costly Information." Journal of Economics and Management Strategy. 2008. Vol. 17, No. 3: 607-631. (Working paper)