Concept Architecture
Concept
Theoretically, the Gini Coefficient for Health is a measure of inequality that quantifies the extent to which the distribution of a health variable differs from perfect equality across individuals or populations. It is derived from welfare economics and the Lorenz curve framework and exists to summarise health inequality using a single numerical measure. The coefficient reflects relative inequality in health outcomes, health status or health-related quality of life, independent of the average level of health.
Mathematically, the Gini Coefficient is defined as the ratio of the area between the Lorenz curve and the line of perfect equality to the total area beneath the line of perfect equality. The coefficient ranges from zero, indicating complete equality, to one, indicating maximum inequality, although values are often substantially lower in empirical health applications.
In practice, the Gini Coefficient for Health is estimated using individual or population-level health data, including life expectancy, health utility values, disability-adjusted life years or other health indicators. In health economics it is used to quantify health inequalities, compare distributions across populations or time periods, and evaluate the equity implications of health policies and interventions.
Purpose
Used to quantify inequality in the distribution of health outcomes, compare health inequalities between populations, monitor changes over time and support equity assessment within health economic and public health evaluations.
Mathematical Formulae
Primary Formula
G = (????� ????� |x? ? x?|) / (2n�?)
where:
- G = Gini Coefficient
- x?, x? = health outcome for individuals i and j
- n = number of individuals
- ? = mean health outcome
Supporting Formulae
Lorenz curve definition:
G = 1 ? 2??? L(p) dp
where:
- L(p) = Lorenz curve
- p = cumulative proportion of the population
Related Mathematical Methods
- Lorenz Curve Analysis
- Distributional Cost-Effectiveness Analysis
- Equity Analysis
- Concentration Curve Analysis
- Inequality Measurement
Example
Five individuals have health utility values of 0.50, 0.70, 0.80, 0.90 and 1.00.
Mean health utility:
? = 0.78
Using the Gini Coefficient formula:
G � 0.128
The result indicates a relatively low but measurable degree of inequality in the distribution of health within the population.
Excel Implementation
| Function | Example Formula | Health Economics Application |
|---|---|---|
| SORT | =SORT(B2:B101) | Orders health observations before constructing the Lorenz curve. |
| AVERAGE | =AVERAGE(B2:B101) | Calculates the mean health outcome. |
| SUM | =SUM(B2:B101) | Calculates total health for cumulative shares. |
| ABS | =ABS(B2-C2) | Calculates pairwise absolute differences when implementing the analytical formula. |
| SUMPRODUCT | =SUMPRODUCT(...) | Computes pairwise summations required for the Gini Coefficient. |
VBA (Optional)
Automate calculation of the Gini Coefficient and generation of Lorenz curves for multiple health outcome datasets.
Sources
- Gini C. Variabilit� e Mutabilit�. 1912.
- Wagstaff A, Paci P, van Doorslaer E. On the Measurement of Inequalities in Health. Social Science & Medicine. 1991.
- O'Donnell O, van Doorslaer E, Wagstaff A, Lindelow M. Analyzing Health Equity Using Household Survey Data.
- Cowell FA. Measuring Inequality.
- Asaria M, Griffin S, Cookson R. Distributional Cost-Effectiveness Analysis: A Tutorial. Health Economics.
Related Concepts (2)
Library
Publications
1
Fair Society, Healthy Lives: The Marmot Review (Strategic Review of Health Inequalities in England Post-2010) — Michael Marmot, Peter Goldblatt, Jessica Allen, et al., 2010 Edition ed., 2010 (The Marmot Review / UCL Institute of Health Equity)
The landmark strategic review of health inequalities in England, articulating the social determinants of health and the "social gradient" and setting out six policy objectives for reducing inequalities — the defining reference for health-inequalities policy in the UK.
Frequently Asked Questions (6)
What is the health Gini coefficient?
An adaptation of the Gini coefficient, originally measuring income inequality, applied to measure inequality in a health outcome, such as life expectancy.
Source: Le Grand 1987
What is the Gini coefficient applied to health?
The health Gini coefficient adapts the Gini coefficient, originally a measure of income inequality, to measure inequality in a health outcome, such as life expectancy or age at death, across a population. It summarises how unequally the health outcome is distributed in a single figure between zero and one, where zero indicates that everyone has the same and higher values indicate greater inequality. It captures dispersion in health across individuals, regardless of their socioeconomic position.
Source: Le Grand 1987
How is the health Gini coefficient calculated?
Like the income Gini, it is derived from the Lorenz curve, which plots the cumulative share of the health outcome against the cumulative share of the population ranked by that outcome. The coefficient equals twice the area between this curve and the line of perfect equality, giving a value from zero, complete equality, to one, maximum inequality. Applied to health, the population is ranked by the health outcome itself rather than by income.
Source: Le Grand 1987
How does the health Gini differ from the concentration index?
The health Gini measures inequality in health across individuals ranked by their own health, capturing pure dispersion regardless of socioeconomic position. The concentration index instead ranks individuals by socioeconomic position and measures how health varies across that ranking, capturing socioeconomic inequality in health. The health Gini shows how unequally health is distributed; the concentration index shows whether that inequality favours the better or worse off, so the two answer different equity questions.
Source: Le Grand 1987
What are the limitations of the health Gini coefficient?
The health Gini captures the overall dispersion of a health outcome but not whether the inequality is socioeconomically patterned, so it cannot show whether the worse health falls on poorer groups, which is often the equity concern. It requires health to be measured on a suitable scale, and outcomes such as age at death behave differently from income, complicating interpretation. Like any single index, it summarises the distribution in one figure that can obscure where inequality lies.
Source: Le Grand 1987
Why apply the Gini coefficient to health?
Applying the Gini to health provides a summary measure of how unequally health is distributed in a population, allowing inequality in health to be quantified, compared across populations, and tracked over time, much as the income Gini does for income. It draws attention to the distribution of health, not only its average, which two populations with the same mean health but different spreads would share. It thus supports the study of health inequality as distinct from average health.
Source: Le Grand 1987
Trust Record
Verified by Dr Darrin Baines
British health economist
Professional identity: darrinbaines.org
Verification date: 27 Aug 2025
Content version: 1.0.0
Canonical Identity
- Term code
- HE-EE-HE-006
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