Compare methods

	Lifespan Inequality	Healthy Life Expectancy
Field	Demography	Demography
Family	Process / pipeline	Survival analysis
Year of origin	2003	1971
Originator	Lifespan-variation literature; life disparity formalized by Vaupel & Canudas-Romo	Daniel F. Sullivan (Sullivan method); developed by the WHO/REVES tradition
Type	Measures of variability in the age-at-death distribution	Health-expectancy estimator partitioning life expectancy into healthy and unhealthy years
Seminal source	Vaupel, J. W., & Canudas-Romo, V. (2003). Decomposing change in life expectancy: A bouquet of formulas in honor of Nathan Keyfitz's 90th birthday. Demography, 40(2), 201–216.	Sullivan, D. F. (1971). A single index of mortality and morbidity. HSMHA Health Reports, 86(4), 347–354.
Aliases	Lifespan Variation, Life Disparity, Variation in Age at Death	HALE, Health-Adjusted Life Expectancy, Disability-Free Life Expectancy
Related	4	4
Summary	Lifespan inequality measures how unequally length of life is distributed within a population — the spread of the life-table ages at death, not just their average. Two populations can share the same life expectancy yet differ sharply in how predictable death is: in one nearly everyone reaches old age, in the other deaths are scattered across all ages. A family of measures — life disparity (e†), the standard deviation of age at death, the life-table Gini coefficient, and Keyfitz entropy — quantifies this dispersion, complementing life expectancy with a measure of how fairly survival is shared.	Healthy life expectancy partitions ordinary life expectancy into the years a person can expect to live in good health and the years expected to be lived with disability or ill health. Building on the life table, the classic Sullivan method weights each age interval's person-years by the prevalence of good health, so the resulting expectancy answers not just 'how long will people live?' but 'how many of those years will be healthy?'. It has become a headline summary of population health, reported by the World Health Organization as HALE and tracked alongside life expectancy to judge whether longer lives are also healthier lives.