Welcome to my research web page. With a focus on innovation, pricing, quality, and shortages, my work aims to drive positive change in health care.

I was the lead author of two articles that became law. In a 2006 article, we proposed the Food and Drug Administration’s priority review voucher program which became law in 2007. In a 2015 article, we proposed the Environmental Protection Agency’s vector expedited review voucher program which became law in 2022.

Priority review vouchers

I was lead author of a 2006 article proposing the priority review voucher program to encourage innovation for neglected diseases (Ridley et al. 2006). Thanks to collaboration with Senators, the law was enacted in 2007. The FDA has awarded more than 60 vouchers and vouchers sell for about $100 million each, so we created a multi-billion dollar market and encouraged new life-saving drugs. For more information about the program, please visit the voucher page.


Eli Liebman and I have been studying drug and vaccine shortages since he was a doctoral candidate at Duke University. We examined causes and identified solutions. One cause of shortages is low and inflexible pricing and reimbursement. One way to mitigate a shortage is through rationing which we examine in the context of a pediatric vaccine shortage.


Government policies play a pivotal role in shaping drug launch prices and price changes. My research has delved into the relationship between Medicare reimbursement and drug launch prices, as well as the regulation of price increases. I have also proposed a simple tool for forecasting market share in the US pharmaceutical market.


There are many mechanisms available to government agencies seeking to promote drug development for otherwise neglected diseases. One mechanism is a prize such as the aforementioned priority review vouchers. Another mechanism is direct funding of research by government agencies. However, we show that across countries, some governments free ride, diverting funds to other diseases and purposes. Another mechanism is a transferable exclusivity voucher in which a drug developer is rewarded with longer market exclusivity for a different drug. However, exclusivity delays generic entry and thus delays savings. We show that if governments and insurers pay almost all of the costs of the most expensive drugs, though, then exclusivity vouchers are not so different from direct government funding.

Vector expedited review vouchers

Building on the success of the priority review voucher, we proposed vector expedited review vouchers in a 2017 article. Our proposal became law in 2022. The aim of the program is to encourage innovation for the products that stop disease-carrying vectors, like mosquitos. Under the program, the maker of a pesticide to treat bed nets receives a voucher for faster regulatory review at the US Environmental Protection Agency for a different product.


We often take for granted that the medicines we use are safe. I am currently engaged in a project focusing on drug quality and FDA oversight. I have also examined how manufacturers monitor drug safety.


When businesses cluster, they engage in more intense price competition. So why cluster? We show that 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.

For more information, see my Google Scholar page.