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

I am interested in innovationlocation, and pricing, especially in health care.


In 2006 we proposed a priority review voucher (Ridley et al. 2006) program to encourage innovation for neglected diseases. We worked with members of the Senate for passage of the voucher law in 2007. The FDA has awarded more than 30 vouchers and vouchers typically sell for about $100 million each, so we created a multi-billion dollar market and encouraged new drugs that save lives for people around the world. 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.


How does government regulation and reimbursement affect drug prices and shortages? 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?


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.