TABLE 1—

Ecological Measures Derived From Year 2000 US Census Tract Data

Measure	Operational Definition	Summary File	Census Variable
Demographic
Asian race	Percentage of population in census tract that self-reports Asian race (1 race only, non-Hispanic)	1	P4
Black race	Percentage of population in census tract that self-reports black race (1 race only, non-Hispanic)	1	P4
Hispanic ethnicity	Percentage of population in census tract that self-reports Hispanic ethnicity	1	P4
Immigration	Percentage of population that was born outside the United States	3	P21
Education: Low attainment	Percentage of persons 25 years and older with less than a high-school diploma	3	P37
Occupation: Unemployment	Percentage of persons aged 16 and older in the labor force who are unemployed	3	P43
Economy: Median income	Median household income for census tract in 1999	3	P53
Housing
Crowded households	Percentage of households with > 1 person per room	3	H20
Population density	Number of people per square mile	1	P1

Note. P = population subjects; H = housing subjects.