Preliminary Steps toward Developing a Sound Research Design for Analyzing the Spatial Distribution of Commercial Hazardous Waste Facilities in Wayne County, Michigan: Part I March 11, 1998 NRE 501 Robin Saha

General Research Question Are low income and minority populations disproportionately exposed to the risks associated with commercial hazardous waste facilities in Wayne County, Michigan?

Research Design Issues Defining geographic areas of impact (“impact zones” or “ host neighborhoods”) Selecting a geographic unit of analysis (census tracts versus block groups)

Location of Wayne County, Michigan

STUDY AREA AND TSDF LOCATIONS Wayne County, Michigan

Considerations in Defining Impact Zones (Design Issue #1) Proximity of known or potential impacts Inverse relationship between distance and impact (social, psychological, economic, environmental, and health ) Size and shape of geographic units for which demographic data are available Previous research and comparability with other studies

DESIGN ISSUE #2 Considerations in Selecting an Appropriate Unit of Analysis How different units affect the delineation of host neighborhoods in terms of how well they approximate circular areas Want to create host neighborhoods (“impact zones”) that are as equivalent as possible in size and shape (equidistant from hazardous waste facilities) -- inter-case consistency

Census Tracts with TSDFs

Census Tracts at Least Partially within 1/2 Mile Circle Centered at TSDFs

Census Tracts at Least Partially within 1.0 Mile Circle Centered at TSDFs

1990 Census Tracts Partially within 1.5 Mile Circle Centered at TSDFs

1990 Census Tracts at least Half within 1.5 Mile Circle Centered at TSDFs

Number of Census Tracts Partially within and at Least Half within 1.5 Mile Radius of TSDFs

Area in Decimal Degrees of Census Tracts Partially within and at Least Half within 1.5 Mile Radius of TSDFs

Area of Census Tracts Partially within and at Least Half within 1.5 Mile Radius of TSDFs, as a Percentage of Wayne County

Delineation of Host Neighborhood as Census Tracts Partially Encompassed by Circle of 1.0 Mile Radius #

Delineation of Host Neighborhood as Census Tracts with Area at Least Half within Circle of 1.0 Mile Radius #

Census Tracts Partially within 1.5 Mile Circle Centered at Env’l Waste Control

Census Tract at Least Half within 1.5 Mile Circle Centered at Env’l Waste Control

Block Groups Partially within 1.5 Mile Circle Centered at Env’l Waste Control

Block Groups At Least Half within 1.5 Mile Circle Centered at Env’l Waste Control

Census Tracts Partially within 1.5 Mile Circle Centered at ChemMet

Block Groups Partially within 1.5 Mile Circle Centered at ChemMet

Census Tracts At Least Half within 1.5 Mile Circle Centered at ChemMet

Block Groups At Least Half within 1.5 Mile Circle Centered at ChemMet

Census Tracts within 1.5 Miles of City Environmental Facility X

Block Groups within 1.5 Miles of City Environmental Facility X

“Underlap” and Overlap of Census Tracts within 1.5 Miles of City Environmental X

“Underlap” and Overlap of Block Groups within 1.5 Miles of City Environmental X

Area As a Percentage of 1.5 Mile Circle of Underlap and Overlap for City Environmental

Comparison of Host Neighborhood Delineations Using Census Tracts and Block Groups

Total Population in Host Neighborhoods Using Tracts vs. Combination of Tracts and Block Groups

Selected Demographics of Host Neighborhoods Using Tracts vs. Combination of Tracts and Block Groups

Conclusions Regarding Host Neighborhood Delineations Areas within a given radius delineate significantly different host neighborhoods using partially vs. mostly circumscribed geographic units (tracts or block groups) Host neighborhood shape and size can (but do not always) vary significantly depending on whether tracts or block groups are used and urban vs. non-urban locations Tract/block group differences appear to be insignificant for highly urbanized locations (based on City Env’l TSDF) Need to repeat analysis for other host neighborhoods, especially for suburban and rural locations

Conclusions Regarding Units of Analysis Preliminary findings suggest choice of using census tracts or block groups can significantly influence demographic results These differences need be more carefully assessed before research design decisions regarding most appropriate unit of analysis can be made Methods for estimating demographic data in “underlap” and overlap areas may address both research design issues

STUDY AREA AND TSDF LOCATIONS Wayne County, Michigan

Area in Square Miles of Underlap and Overlap for City Environmental

Census Tracts at Least Partially within 2.0 Mile Circle Centered at TSDFs