Compare methods

	Active Life Expectancy Estimation	Dependency Ratio
Field	Social Gerontology	Demography
Family	Survival analysis	Process / pipeline
Year of origin	1983	1956
Originator	Sidney Katz, Laurence G. Branch and colleagues	Standard demographic practice (United Nations / national statistical offices)
Type	Life-table estimator partitioning remaining life into active and dependent years	Ratio summarizing the age structure of economic dependency
Seminal source	Katz, S., Branch, L. G., Branson, M. H., Papsidero, J. A., Beck, J. C., & Greer, D. S. (1983). Active life expectancy. New England Journal of Medicine, 309(20), 1218-1224.	Preston, S. H., Heuveline, P., & Guillot, M. (2001). Demography: Measuring and Modeling Population Processes. Blackwell. ISBN: 9781557864512
Aliases	ALE, Disability-Free Years Expectancy, Independent Life Expectancy, Active vs Dependent Life Years	Age dependency ratio, Youth and old-age dependency ratio, Total dependency ratio, Bağımlılık Oranı
Related	4	4
Summary	Active life expectancy (ALE) estimates how many of an older person's remaining years are expected to be lived in an active, independent state — free of disability in basic activities of daily living — as opposed to a dependent state requiring help. Introduced by Sidney Katz, Laurence Branch, and colleagues in 1983 in the New England Journal of Medicine, it answered a question that ordinary life expectancy cannot: not just how long people live, but how much of that life is lived in good functional health. The method combines age-specific mortality with the prevalence or transitions of ADL disability within a life-table framework, partitioning total remaining life into active and dependent components that sum to overall life expectancy. Katz and colleagues showed, using data from older adults in Massachusetts, that active life expectancy declines faster than total life expectancy with age and differs across groups. The concept reframed the goal of aging policy from merely extending lifespan to extending the active, independent portion of it. It launched the broader field of health expectancy measures and remains foundational to studying the compression or expansion of late-life morbidity.	The age dependency ratio is a simple summary measure of a population's age structure that expresses the number of people in 'dependent' age groups — children and the elderly — relative to those of working age, conventionally per 100 working-age persons. It is split into a youth dependency ratio and an old-age dependency ratio, and it is among the most widely used demographic indicators of the potential economic burden an age structure places on its productive population.