مقایسهٔ روش‌ها

	Years of Life Lost	Lifespan Inequality
حوزه	جمعیت‌شناسی	جمعیت‌شناسی
خانواده	Process / pipeline	Process / pipeline
سال پیدایش	1994	2003
پدیدآور	Premature-mortality measure; standardized form by Christopher Murray (Global Burden of Disease)	Lifespan-variation literature; life disparity formalized by Vaupel & Canudas-Romo
نوع	Burden-of-disease measure of life-years lost to early death	Measures of variability in the age-at-death distribution
منبع بنیادین	Murray, C. J. L. (1994). Quantifying the burden of disease: the technical basis for disability-adjusted life years. Bulletin of the World Health Organization, 72(3), 429–445.	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.
نام‌های دیگر	YLL, Years of Potential Life Lost, Premature Mortality Years Lost	Lifespan Variation, Life Disparity, Variation in Age at Death
مرتبط	4	4
خلاصه	Years of life lost (YLL) measures the burden of premature mortality by counting, for every death, how many additional years the person could have expected to live had they survived to a reference life expectancy. Summed over all deaths, YLL turns a count of deaths into a count of lost life-years, so that deaths at young ages weigh far more heavily than deaths in old age. It is the mortality half of the disability-adjusted life year (DALY) and a core metric of the Global Burden of Disease studies, letting analysts rank diseases and injuries by how much potential life they destroy rather than merely by how many people they kill.	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.