Do measures matter? Comparing surface-density-derived and census-tract-derived measures of racial residential segregation

Abstract

BackgroundRacial residential segregation is hypothesized to affect population health by systematically patterning health-relevant exposures and opportunities according to individuals' race or income. Growing interest into the association between residential segregation and health disparities demands more rigorous appraisal of commonly used measures of segregation. Most current studies rely on census tracts as approximations of the local residential environment when calculating segregation indices of either neighborhoods or metropolitan areas. Because census tracts are arbitrary in size and shape, reliance on this geographic scale limits understanding of place-health associations. More flexible, explicitly spatial derivations of traditional segregation indices have been proposed but have not been compared with tract-derived measures in the context of health disparities studies common to social epidemiology, health demography, or medical geography. We compared segregation measured with tract-derived as well as GIS surface-density-derived indices. Measures were compared by region and population size, and segregation measures were linked to birth record to estimate the difference in association between segregation and very preterm birth. Separate analyses focus on metropolitan segregation and on neighborhood segregation.ResultsAcross 231 metropolitan areas, tract-derived and surface-density-derived segregation measures are highly correlated. However overall correlation obscures important differences by region and metropolitan size. In general the discrepancy between measure types is greatest for small metropolitan areas, declining with increasing population size. Discrepancies in measures are greatest in the South, and smallest in Western metropolitan areas. Choice of segregation index changed the magnitude of the measured association between segregation and very preterm birth. For example among black women, the risk ratio for very preterm birth in metropolitan areas changed from 2.12 to 1.68 for the effect of high versus low segregation when using surface-density-derived versus tract-derived segregation indices. Variation in effect size was smaller but still present in analyses of neighborhood racial composition and very preterm birth in Atlanta neighborhoods.ConclusionCensus tract-derived measures of segregation are highly correlated with recently introduced spatial segregation measures, but the residual differences among measures are not uniform for all areas. Use of surface-density-derived measures provides researchers with tools to further explore the spatial relationships between segregation and health disparities.

By all measures: an examination of the relationship between segregation and health risk from air pollution

“…However, when spatial correlation is controlled for by using clustered standard errors, the relative proportion of African-Americans in a block group loses significance for evenness measures primarily, which impacts the significance of the interaction effect. Although research has shown that health outcomes using spatial measures of segregation are no different when compared to standard measures of segregation (Kramer et al 2010), these results suggests that if future studies of health risk from air pollution, especially those utilizing measures of evenness, spatial models should be considered.…”

Residential Racial Composition, Spatial Access to Care, and Breast Cancer Mortality among Women in Georgia

“…The tract-level RRC is the neighborhood component used to measure the metropolitan isolation index, which assesses the residential exposure or isolation of minority communities to other groups across metropolitan space. [34][35][36] We defined "spatial access to cancer care" as the local availability of cancer treatment and care. We focused on potential spatial access, which concerns reasonable possible use, rather than revealed access, which refers to actual service use because the GCCR does not provide information on the physical address of the specific treatment facilities in which participants received care.…”

At which geographic scale does ethnic diversity affect intra-neighborhood social capital?

“…5 A more detailed description on computing egocentric neighborhoods can be found elsewhere (e.g., Kramer et al, 2010;Reardon et al 2008;Reardon and O'Sullivan 2004). This may be part of the reason why effect sizes of diversity on opposition to non-western neighbors are not very substantial.…”

“…Recent studies in other fields (e.g., geography, health and criminality) introduced egohoods as definition of the relevant local environment (Chaix 2009, Chaix et al, 2012Kramer et al, 2010;Lee et al, 2008;Reardon et al, 2008). Egohoods are individually oriented living environments that can be visualized as circles with different radii, with the individual at the center of its own locality.…”