Reconceptualizing Measures of Black-White Disparity in Infant Mortality in US Counties

The magnitude of Black-White differences in infant mortality rates varies considerably across U.S. counties. Many prior studies of racial disparities in infant mortality rely on rate ratios (RRs) and rate differences (RDs) to measure relative and absolute inequalities in the risk of infant mortality between Black and White infants. In this paper, I draw on linked birth and death records from 2004 to 2013 to systematically evaluate RRs and RDs as tools for assessing variation in Black-White disparities in infant mortality across U.S. counties. I present evidence that both metrics have limitations in identifying counties that can serve as a model for, or target of, institutional interventions. For example, rather than reflecting an advantaged position for Black infants, counties with the lowest RRs tend to be places with high White infant mortality rates. I then introduce a new approach to measuring relative and absolute inequalities in infant mortality and evaluate the utility of these new metrics compared to conventional approaches.