Representation and Hesitancy in Population Health Research: Evidence from a COVID-19 Antibody Study

We examine why minority and poor households are often underrepresented in studies that require active participation. Using data from a serological study with randomized participation incentives, we find large participation gaps by race and income when incentives are low, but not when incentives are high. We develop a framework for using randomized incentives to disentangle the roles of hesitancy and non-contact in driving the participation gaps, and find that hesitancy is the predominant factor. Hesitancy rates strongly correlate with hospitalization rates and COVID-19 risk, suggesting that individuals facing higher health risks may be underrepresented in studies with low incentives.