Inequality-adjusted HDI
Also known as: IHDI, Inequality-adjusted Human Development Index, Atkinson-adjusted HDI, Distribution-sensitive HDI
The Inequality-adjusted Human Development Index (IHDI) extends the Human Development Index by accounting for how achievements in health, education, and income are distributed across a population, not just their averages. Designed by Sabina Alkire and James Foster for the UNDP and introduced in the 2010 Human Development Report, it discounts each HDI dimension by the inequality observed within it, using an Atkinson-class inequality measure. When there is no inequality the IHDI equals the HDI; as inequality rises the IHDI falls below it, and the percentage gap — the 'loss' — measures how much human development is eroded by being unequally shared.
Key highlights
- Makes the HDI distribution-sensitive, so a country is rewarded for spreading health, education, and income equitably rather than concentrating them.
- The IHDI equals the HDI under perfect equality and the gap between them yields an interpretable 'loss due to inequality' headline figure.
- Uses an Atkinson-class measure that is subgroup-decomposable and that handles inequality in each dimension separately, so the source of the loss can be identified.
- Built directly on the familiar HDI structure, so it is easy to communicate as 'the HDI a country would have if achievements were equally distributed'.
Intuition
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How it works
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When to use it
Use the IHDI when the average picture given by the HDI is not enough and you want a distribution-sensitive measure that rewards equitably shared human development and penalizes concentration. It is the right companion to the HDI for comparing how well countries spread health, education, and income, for tracking whether progress is inclusive, and for highlighting the inequality 'loss' as an advocacy and monitoring figure. It requires household-level distributional data for each dimension, which is less universally available than the aggregate indicators behind the HDI, and like the HDI it remains a national summary rather than a measure of poverty, gender gaps, or sustainability.
Strengths & limitations
- Makes the HDI distribution-sensitive, so a country is rewarded for spreading health, education, and income equitably rather than concentrating them.
- The IHDI equals the HDI under perfect equality and the gap between them yields an interpretable 'loss due to inequality' headline figure.
- Uses an Atkinson-class measure that is subgroup-decomposable and that handles inequality in each dimension separately, so the source of the loss can be identified.
- Built directly on the familiar HDI structure, so it is easy to communicate as 'the HDI a country would have if achievements were equally distributed'.
- Requires household-level distributional data for all three dimensions, which is unavailable or low-quality in many countries, forcing imputation and limiting comparability.
- It is association-insensitive in its standard form: it captures inequality within each dimension separately but not the overlap (whether the same people are deprived across dimensions).
- The choice of inequality-aversion parameter (set to one) is a normative judgment that shapes how strongly inequality is penalized.
- Like the HDI it remains a national average construct and says nothing about poverty incidence, gender gaps, or environmental sustainability.
Common pitfalls
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Applications
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Frequently asked
What does the inequality 'loss' in the IHDI mean?
The loss is the percentage by which the IHDI falls short of the HDI: L = (HDI - IHDI)/HDI. It quantifies how much potential human development is lost because achievements in health, education, and income are not equally distributed. A loss of 0 percent means perfectly equal distribution and IHDI equal to HDI; a loss of, say, 25 percent means a quarter of the country's average human development is, in effect, forfeited to inequality. Comparing losses across countries shows where development is most unequally shared.
Why does the IHDI use the Atkinson index rather than the Gini coefficient?
The Atkinson measure used in the IHDI is based on the ratio of the geometric mean to the arithmetic mean of individual achievements, which makes it subgroup-decomposable and gives it a clean welfare interpretation through the equally distributed equivalent. This lets each HDI dimension be discounted by (1 - A_x) and recombined with the same geometric-mean machinery as the HDI. The Gini coefficient, while widely used, is not subgroup-decomposable in the same convenient way and does not slot as cleanly into the multiplicative structure of the index.
Why is the IHDI called 'association-insensitive'?
The standard IHDI measures inequality in each dimension separately and then discounts each dimension, so it captures how unequal health is, how unequal education is, and how unequal income is, but not whether the same individuals are simultaneously disadvantaged across all three. Two societies with identical within-dimension inequalities receive the same IHDI even if in one the deprivations pile on the same people and in the other they are spread around. Capturing that overlap requires a joint, individual-level measure such as the Multidimensional Poverty Index.
Sources
- 1.Alkire, S., & Foster, J. (2010). Designing the Inequality-Adjusted Human Development Index (IHDI). OPHI Working Paper 37 / Human Development Research Paper 2010/28. UNDP Human Development Report Office, New York.
- 2.UNDP (2022). Human Development Report 2021-22, Technical Notes. United Nations Development Programme, Human Development Report Office, New York.
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ScholarGate. (2026, June 22). Inequality-adjusted HDI. ScholarGate. https://scholargate.app/development-studies/inequality-adjusted-hdi