In order to estimate risk ratios, it was necessary to merge death record data with corresponding records on the living population. Population data were culled from 1% samples of individual-level data from the 1990 U.S. Census, the 2000 U.S. Census, and the 2004 American Community Survey (ACS). The ACS is an ongoing population survey conducted by the U.S. Census Bureau, phased in as a replacement to the long form of the U.S. census. The 2004 sample contained data on 353,220 individuals in our targeted age-range, or 0.44% of the U.S. population. All population data were obtained from the Integrated Public Use Microdata Series maintained by the Minnesota Population Center (Ruggles et al., 2010).
