Table 1.
Area-Based Socioeconomic Variables Considered for Inclusion in the Analysis
| Variable | Definition | Data Source |
|---|---|---|
| Low-income households | % households with income <$25000 (approximates <50% of median US household income) | ACS |
| High-income households | % households with income ≥$200000 (approximates ≥400% of median US household income) | ACS |
| Poverty | % persons below poverty level in past 12 months | ACS |
| Income inequality index | Gini coefficienta | ACS |
| Crowding | % of occupied households with >1 person/room | ACS |
| Expensive homes | % of owner-occupied housing units ≥$750000 (approximates ≥400% of median value) | ACS |
| Rural areas | % population living in rural area | 2010 Census |
| Low education | % people aged ≥25 y with <12th grade education (includes 12th grade, no diploma) | ACS |
| High education | % people aged ≥25 y with at least bachelor’s degree | ACS |
| Health insurance | % persons with health insurance coverage | ACS |
| Medically underserved area | Based on % of population with income below poverty level, percent of population with age >65 y, infant mortality, and availability of primary care providers | HRSA |
Abbreviations: ACS, 2008–2012 American Community Survey; HRSA, Health Resources and Services Administration.
aGini coefficient ranges from 0 to 1, with extreme values when income is uniformly distributed across all members of population (Gini coefficient = 0) or all income belongs to a single person (Gini coefficient = 1).