Because household poverty status was available only at the block group level, we aggregated census block-level land cover characteristics, and the weighted distribution of each of the eight subpopulations defined by race/ethnicity and housing tenure, at the census block group level for analysis:
Specifically, if at least half of a subpopulation lived in a census block with no tree canopy, or at least half of a subpopulation lived in a census block with at least 50% impervious surface, then the subpopulation was classified at the census block group level as living with no tree canopy or with impervious surface, respectively.
When the 1990 census is on the line in 1992, data will be available at the census block group level
, a unit containing approximately 50 to 100 households.
Census 2000 data on household median income (measured in tens of thousands) and proportion receiving public assistance, which were obtained at the census block group level
Unlike the contours at ZIP code level, the contours at census block group level
highlight areas in central Durham, characterized by a higher percentage of minorities and a lower median household income, as potential hot spots for exposure.
In a later statewide ecologic study, we analyzed childhood cancer rates with respect to traffic density at the census block group level
and, consistent with other more recent studies focused on traffic measures (Langholz et al.