Population density and racial differences in the performance of emergency medical services

This paper analyzes the existence and scope of possible racial differences/disparities in the provision of emergency medical services (EMS) response capability (time from dispatch to arrival at the scene and level of training of the responding team) using data on approximately 120,000 cardiac incidents in the state of Mississippi during 1995-2004. The conceptual framework and empirical analysis focus on the likely effects of population density on the efficient production of EMS as a local public good subject to congestion, and on the need to control adequately for population density to avoid bias in testing for racial differences. Models that control for aggregate population density at the county-level indicate "reverse" disparities: faster estimated response times for African-Americans than for whites. When a refined county-level measure of population density is used that incorporates differences in African-American and white population density by Census tract, the reverse disparity in response times disappears. There also is little or no evidence of race-related differences in the certification level of EMS responders. However, there is evidence that, controlling for response time, African-Americans on average were significantly more likely to be deceased than whites upon EMS arrival at the scene. The overall results are germane to the debate over the scope of conditioning variables that should be included when testing for racial disparities in health care.