I write about health care innovation, production, and prices. I am interested in how to encourage product makers to develop products that would otherwise be neglected. 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.

I am not only interested in why companies make new products, but also in the quality of those products and why they sometimes stop making products: I write about drug and vaccine shortages. One factor that can precede a shortage is low prices. I write about drug prices, including launch prices and patient prices (copayments). Early in my career, I was interested in where businesses locate.

Priority review vouchers

I was lead author of a 2006 article which became law in 2007. We proposed a priority review voucher program to encourage innovation for neglected diseases(Ridley et al. 2006). We worked with members of the Senate for passage of the voucher law in 2007. The FDA has awarded more than 50 vouchers and vouchers sell for about $100 million each, so we created a multi-billion dollar market and encouraged new drugs that save lives. You can read more at this voucher page.

Vector expedited review vouchers

Following the success of the priority review voucher, we proposed vector expedited review vouchers in a 2017 article. Our proposal became law in 2022. 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.


To encourage drug development for neglected diseases, government agencies can provide direct funding of clinical trials. However, some government agencies will free ride, diverting funds to other diseases and purposes. Another way to encourage drug development for neglected diseases is to offer transferable exclusivity vouchers.

Safety monitoring

We often take for granted that the medicines we use are safe. I am working on a new project about drug quality and FDA oversight. I have also written about manufacturer efforts to monitor drug safety.


In health care, shortages are surprisingly common. One cause of drug and vaccine shortages is low and inflexible prices. Manufacturers invest little in spare capacity if margins are thin. Rationing has been effective at mitigating the harm from a vaccine shortage, provided that some supply is available from a second manufacturer.


Government policy influences both drug launch prices and price changes.


When businesses 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.

For more information, see my Google Scholar page.