Government regulations influence virtually every interaction between a health care provider and a patient in the United States. Yet researchers have often struggled to capture the systematic role healthcare regulations play in health outcomes.

The Healthcare Openness and Access Project (HOAP), launched in 2016, seeks to fill this gap by measuring the openness and access of healthcare regulations across states. In this paper, we present the evidence-based framework that underpins HOAP’s methodology. The index provides quantifiable measure of healthcare regulations and how they affect health outcomes across US states.