Partitioning the Spatial Spillover Effects of Social Conditions on Mortality: An Example Using US County Data

It has been argued that social conditions are the fundamental determinants of health for those agents who possess them, and this argument has been bolstered by both individual and ecological studies. However, little is known about whether social conditions also benefit others nearby. Using the US county mortality data, we fill this gap by first theorizing the relationships between the social conditions of a county and the mortality of its neighbors with spatial spillover and social relativity perspectives. We then measured social conditions with income inequality, social capital, social affluence and concentrated disadvantage and used spatial Durbin modeling and spatial partitioning technique to examine the effects of these variables on mortality across space. The analytic results suggested that (1) social conditions of a specific county are not only related to its own mortality but also the mortality in neighboring counties; (2) The partitioning results provide evidence for spatial feedback, which underscores the importance of spatial structure underlying the data; and (3) The immediate neighbors (those shared the same boundaries or a vertex) play a more important role in understanding the direct impacts of social conditions on mortality than those neighbors far away. These findings provide new insight to mortality research.