Education, income inequality, and mortality: a multiple regression analysis

OBJECTIVE: To test whether the relation between income inequality and mortality found in US states is because of different levels of formal education. DESIGN: Cross sectional, multiple regression analysis. SETTING: All US states and the District of Columbia (n=51). DATA SOURCES: US census statistics and vital statistics for the years 1989 and 1990. MAIN OUTCOME MEASURE: Multiple regression analysis with age adjusted mortality from all causes as the dependent variable and 3 independent variables—the Gini coefficient, per capita income, and percentage of people aged ⩾18 years without a high school diploma. RESULTS: The income inequality effect disappeared when percentage of people without a high school diploma was added to the regression models. The fit of the regression significantly improved when education was added to the model. CONCLUSIONS: Lack of high school education accounts for the income inequality effect and is a powerful predictor of mortality variation among US states.