Starting more than 30 years ago he has done seminal work in guidelines, mathematical modeling, cost-effectiveness, coverage decisions, medical necessity and performance measurement. He is one of the founders of the "evidence-based" movement, promoting and teaching the application of evidence to guidelines, coverage policies, performance measures and medical necessity. The author of five books and more than 100 first-authored articles, including a series of essays for the Journal of the American Medical Association, his writings span from technical mathematical theories to broad health policy topics. He has received 8 national and international awards in several different fields, including applied mathematics, health technology assessment, health care quality, and outcomes research.