Table 2

Area based socioeconomic measures: constructs and operational definitions, using 1990 US census data30

ConstructOperational definitionCensus variable
*Variables used in the factor analysis: percentage working class, unemployed, < poverty, home ownership, car ownership, no telephone, expensive homes, < high school education, ≥ four years of college education, household crowding, households with only one room, no kitchen, no private plumbing, and also median household income and proportion of total income in the area derived from interest, dividends, and net rent. †Values for “expensive homes” and “median household income” were reversed before computing z score so that a higher score on the SEP index would correspond to a higher degree of deprivation.
Occupational class
    (1) Working class7–Percentage of persons employed in predominantly working class occupations, that is., as non-supervisory employees, operationalised as percentage of persons employed in the following 8 of 13 census based occupational groups: administrative support; sales; private household service; other service (except protective); precision production, craft, repair; machine operators, assemblers, inspectors; transportation and material moving; handlers, equipment cleaners, labourers.P78
    (2) Unemployment–Percentage of persons age 16 and older in the labour force who are unemployed (and actively seeking work)P71
(B) Income
    (3) Median household income–Median household income in year prior to the decennial census (for US in 1989 = $30056)P80A
    (4) Low income39 –Percentage of households with income <50% of the US median household income (that is., <$15000)P80
    (5) High income–Percentage of households with incomes ≥400% of the US median household income (that is, ≥$150000)P80
    (6) Gini coefficient40 –A measure of income inequality, regarding the share of income distribution across the population, calculated using the standard algorithm used by the US Bureau of Census to extrapolate the lower and upper ends of the income distributionP80, P80A, P81
(C) Poverty
    (7) Below poverty30, 47 –Percentage of persons below federally defined poverty line, a threshold which varies by size and age composition of the household, and on average equalled $12647 for a family of 4 in 198930 P117
(D) Wealth
    (8) Expensive homes–Percentage of owner occupied homes worth ≥$300000 (400% of the median value of owned homes in 1989)H61
(E) Education
    (9) Low: < high school–Percentage of persons, age 25 and older, with less than a 12th grade educationP57
    (10) High: ≥4 y of college–Percentage of persons, age 25 and older, with at least 4 years of collegeP57
(F) Crowding
    (11) Crowded households–Percentage of households with ≥1 person per roomH69, H49
(G) Composite measures
    (12) Townsend index38, 41– 42 –UK deprivation measure consisting of a standardised z score combining data on percentage crowding, percentage unemployment, percentage no car ownership, and percentage rentersH69, H49, H40, H8
    (13) Carstairs index37– 38, 43 –UK deprivation measure consisting of a standardised z score combining data on percentage crowding, percentage male unemployment, percentage no car ownership, and percentage low social class (US census categories for: transportation and material moving; handlers, equipment cleaners, and laborers; household service).H69, H49, H40, P78
    (14) Index of Local Economic Resources44 –A “summary index” based on: “white collar employment, unemployment, and family income”P78, P71, P107A
    (15) SEP1–A composite categorical variable based on percentage < poverty, working class, and expensive homes{see above}
    (16) SEP2–A composite categorical variable based on percentage < poverty, working class, and high income{see above}
    (17) factor 1*–A factor pertaining to economic resources; highly correlated with poverty, median household income, home ownership, and car ownership{see above}
    (18) factor 2*–A factor pertaining to occupation and education; highly correlated with percentage working class, < high school, and ≥4 y college{see above}
    (19) SEP index–A summary deprivation measure consisting of a standardised z score combining data on percentage working class, unemployed, < poverty, < high school, expensive homes, and median household income†{see above}