Table.

Questions That Arise in Selecting Health Inequality Measures and Measurement Properties of the Index of Disparity and the Gini Coefficient

Question	Index of Disparity	Gini Coefficient
Comparison
Who is compared against whom or what? Should the comparison be made in terms of health only (univariate) or health and another attribute (bivariate)?	The healthiest group against all other groups	Everyone against everyone
Aggregation
How are differences aggregated at the population level? For bivariate health inequality measures, should the measures be sensitive to inherent ordering of another attribute (eg, income)?	Unweighted addition of difference and sensitive to inherent ordering of attribute	Weighted addition of health share and unweighted addition of difference
Sensitivity to the mean
Should the judgment of inequality be sensitive to the mean level of the population? Absolute measures are translation invariant, meaning that equal absolute difference implies equal degree of inequality, while the equal proportional increase makes inequality larger. Relative measures are scale invariant, meaning that equal proportional difference implies equal degree of inequality, while the equal absolute addition reduces inequality. Intermediate inequality measures consider equal proportional increase makes inequality bigger, while equal absolute addition decreases inequality.	Translation invariant	Scale invariant
Sensitivity to the total population size
Should the judgment of inequality be sensitive to the total population size?	Insensitive	Insensitive
Subgroup considerations
Should the judgment of inequality be sensitive to the subpopulation size? How should the overall inequality of a population correspond to inequalities of subgroups in that population?	Insensitive to the group size	Decomposable