Williams is an applied micro-economist who works on the causes and consequences of technological change in health care markets. Specifically, she studies economic and policy factors that affect medical innovation, and quantifies the impacts of "missing innovation" that could have been beneficial for human health and medicine.[5] She is most well known for her work on the Human Genome Project. In her dissertation research, Williams shows that intellectual property held by the company Celera on human genome sequences had negative consequences for the development of scientific research and genetic tests based on those genes.[6] In some other work, Williams and her co-authors show that pharmaceutical firms under-invest in research in early-stage cancer drugs because they take longer time to get to market, as compared to drugs for late-stage cancer.[5]
In 2015, Williams was made a MacArthur Fellow, a grant given yearly to 25 people around the world to continue work in their fields.[7] Her citation[8] for that award noted:
Heidi Williams is an economist unraveling the causes and consequences of innovation in health care markets. Williams combines finely grained empirical observations and custom-designed data collection methods to build entirely new datasets about technological changes in health care. In addition, her creative methods for determining causal inference, and keen understanding of regulatory law, biological science, and medical research, have allowed her to trace the interplay among institutions, market behavior, and public policy–relevant outcomes.
In June 2021, Williams was a co-recipient of the biennial ASHEcon Medal, an award from the American Society of Health Economists for researchers aged 40 and under who have made significant contributions to the field of health economics.[9][10]