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 October 2015, 7 vouchers had been awarded and 4 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." Correspondence in the 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. Adrian Towse, Eric Keuffel, Hannah E. Kettler and David B. Ridley. 2012. "Drugs and Vaccines for Developing Countries." In: P. Danzon and S. Nicholson, eds. Oxford Handbook of the Economics of the Biopharmaceutical Industry. (Working paper)
  5. 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)
  6. Henry G. Grabowski, David B. Ridley, and Jeffrey L. Moe. 2009. "Priority Review Vouchers to Encourage Innovation for Neglected Diseases." In: K. Eggleston, ed. Prescribing Cultures and Pharmaceutical Policy in the Asia-Pacific. Brookings Institution Press. 347-365.
  7. Jeffrey L. Moe, Henry G. Grabowski, and David B. Ridley. 2009. "FDA Review Vouchers." Correspondence in The New England Journal of Medicine. Vol. 360, No. 8: 837-838.
  8. 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)

Pricing and Marketing

How does the reimbursement price affect shortages? How sensitive is demand to copayments and advertising? How does competition affect generic prices? Do Americans pay higher prices for pharmaceuticals than people in other rich countries? How can we encourage lower prices for poor countries?

  1. Ali Yurukoglu, Eli Liebman, David B. Ridley. 2016. "The Role of Government Reimbursement in Drug Shortages." NBER Working Paper.
  2. David B. Ridley, Xiaoshu Bei, and Eli Liebman. 2016. "No Shot: US Vaccine Prices and Shortages." Health Affairs, 35(2): 235-241. (Working paper)
  3. 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)
  4. David B. Ridley. "Payments, Promotion, and the Purple Pill." Health Economics. 2015. Vol. 24, No. 1: 86-103. (Working paper)
  5. 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.
  6. 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)
  7. David B. Ridley. "International Price Comparisons for Novel and Follow-On Drugs." Value in Health. 2007. Vol. 10, No. 6: 510-511. (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.
  10. David B. Ridley. "Price Differentiation and Transparency in the Global Pharmaceutical Marketplace." Pharmacoeconomics. 2005. Vol. 23, No. 7: 651-658.
  11. David B. Ridley and Kevin A. Schulman. "Differential Pricing of Pharmaceuticals in the Internet Age." Journal of Ambulatory Care Management. 2004. Vol. 27, No. 3: 210-214.

Health Care Costs

How costly is post-approval drug safety? How costly is hospital inefficiency?

  1. David B. Ridley, Judith M. Kramer, Hugh H. Tilson, Henry G. Grabowski, and Kevin A. Schulman. "Spending on Postapproval Drug Safety." Health Affairs. 2006. Vol. 25, No. 2: 420-428.
  2. Bimal R. Shah, Shelby D. Reed, Jennifer Francis, David B. Ridley, and Kevin A. Schulman. "The Cost of Inefficiency: A Look at US Hospital Overhead Costs from 1985-1997." Journal of Health Care Finance. 2003. Vol. 30: 1-9.


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)