THE RELATION BETWEEN INCOME AND MORTALITY IN US BLACKS AND WHITES

Differential mortality exists in the United States both between racial /ethnic groups and along gradients of socioeconomic status. The specif ication of statistical models for processes underlying these observed disparities has been hindered by the fact that social and economic qua ntities are distributed in a highly nonrandom manner throughout the po pulation. We sought to provide a substantive foundation for model deve lopment by representing the shape of the income-mortality relation by racial/ethnic group. We used data on black and white men and women fro m the longitudinal component of the National Health Interview Survey ( NHIS), 1986-1990, which provided 1,191,824 person-years of follow-up a nd 12,165 mortal events. To account for family size when considering i ncome, we used the ratio of annual family income to the federal povert y line for a family of similar composition. To avoid unnecessary categ orizations and prior assumptions about model form, we employed kernel smoothing techniques and calculated the continuous mortality surface a cross dimensions of adjusted income and age for each of the gender and racial/ethnic groups. Representing regions of equal mortality density with contour plots, we observed interactions that need to be accommod ated by any subsequent statistical models. We propose two general theo ries that provide a foundation for more elaborate and testable hypothe ses in the future.