Relation between income inequality and mortality: empirical demonstration

Area of Science:

• Public Health
• Sociology
• Epidemiology

Background:

• Observed population-level associations suggest income inequality impacts mortality rates.
• The 'statistical artifact' hypothesis posits these associations arise from individual-level income-mortality relationships.
• This study investigates the validity of the statistical artifact explanation.

Purpose of the Study:

• To evaluate the extent to which population-level income inequality and mortality associations are statistical artifacts.
• To differentiate between artifactual and genuine effects of income inequality on mortality.

Main Methods:

• Utilized indirect 'what if' simulations based on individual-level income and mortality risk data.
• Constructed hypothetical state-level mortality data assuming the statistical artifact argument was entirely correct.
• Employed 1990 US census data, Centers for Disease Control and Prevention mortality data, and National Longitudinal Mortality Study regressions.

Main Results:

• Simulated hypothetical mortality showed a weaker association with income inequality compared to observed mortality.
• The statistical artifact argument could not fully explain the observed correlation between income inequality and mortality.

Conclusions:

• The association between US state-level income inequality and mortality is not entirely explained by statistical artifacts.
• A significant, independent relationship exists between income inequality and mortality at the state level.
• This reinforces the importance of social determinants, including the social environment, in influencing population health.