TABLE 1.
Interpretations of Income Inequality Effects on Health
| Hypothesis | Interpretation |
|---|---|
| Wagstaff and van Doorslaer (2000) | |
| Absolute income hypothesis (AIH) | There is no association between income inequality and health after proper control for absolute income at the individual level. |
| Relative income hypothesis (RIH) | It is income relative to some social group average (which social group is undefined) that is important to health. |
| Deprivation hypothesis (DH) | It is income relative to some poverty standard that is important to health. |
| Relative position hypothesis (RPH) | It is an individual's relative position in the income distribution that is important to health. |
| Income inequality hypothesis (IIH) | There is a direct effect of income inequality on health after control for absolute income. |
| Mellor and Milyo (2002) | |
| IIH (strong version) | For two individuals, A (with high income) and B (with low income), a transfer of income from A to B will improve the health of both. |
| IIH (weak version) | An income transfer will improve the health of B much more than the reduction of health for A, suggesting more potent health effects of income inequality among the poor. |
| Lynch et al. (2000a) | |
| Individual income interpretation | As for the AIH above. |
| Psychosocial interpretation (strong version) | Direct health effects of income inequality represent generalizable psychosocial processes that are among the major determinants of population health in rich countries. |
| Psychosocial interpretation (weak version) | Direct health effects of income inequality represent particular psychosocial processes that influence some health outcomes in rich countries. |
| Neomaterial interpretation | Direct health effects of income inequality result from the differential accumulation of exposures that have their sources in the material world and that do not result directly from perceptions of disadvantage. |