Table 1 Summary of major methods for measuring inequality [9–16]
Measure | Definition |
|---|---|
Ratio | The quotient of rates or values |
Difference | The difference of rates or values |
Effect index | A regression slope |
Population Attributable Risk | A given rate compared to some baseline rate |
Index of dissimilarity | Percent of cases that would have to be redistributed to have the same rate for all SES groups |
Slope Index of Inequality | Slope of the regression line of a health measure against rank ordered SES category |
Relative Index of Inequality | Slope Index of Inequality divided either by the mean or the highest level of the health measure |
Lorenz Curve | Cumulative proportion of the population plotted against cumulative proportion of a health variable; the 45o line represents uniform distribution |
Gini Coefficient | Twice the area between the empirical Lorenz curve and its diagonal, a summary measure of deviation that corresponds to the amount of inequality |
Concentration Curve and Concentration Index | Similar to Lorenz curve and Gini coefficient, but health variable is plotted against ordered socioeconomic status |
Relative Distribution Measures | A more general class of measures that permits direct comparison of two distributions |
Symmetrized Renyi Index | A measure based on entropy that is invariant with respect to a reference group and that permits judgment-weighting based on the perceived importance of disparities |