השוואת שיטות

	Prospective Old-Age Dependency Ratio	Dependency Ratio
תחום	Social Gerontology	דמוגרפיה
משפחה	Survival analysis	Process / pipeline
שנת המקור	2005	1956
הוגה השיטה	Warren C. Sanderson & Sergei Scherbov	Standard demographic practice (United Nations / national statistical offices)
סוג	Demographic ratio using a moving, longevity-based old-age threshold	Ratio summarizing the age structure of economic dependency
מקור מכונן	Sanderson, W. C., & Scherbov, S. (2005). Average remaining lifetimes can increase as human populations age. Nature, 435(7043), 811-813.	Preston, S. H., Heuveline, P., & Guillot, M. (2001). Demography: Measuring and Modeling Population Processes. Blackwell. ISBN: 9781557864512
כינויים	POADR, Prospective Dependency Ratio, Sanderson-Scherbov Dependency Ratio, Remaining-Life-Expectancy Old-Age Ratio	Age dependency ratio, Youth and old-age dependency ratio, Total dependency ratio, Bağımlılık Oranı
קשורות	3	4
תקציר	The prospective old-age dependency ratio (POADR) is a measure of population aging that redefines the onset of old age in terms of remaining life expectancy rather than a fixed chronological age such as 65. Proposed by Warren Sanderson and Sergei Scherbov in a 2005 Nature paper, it rests on the insight that what '65' meant decades ago, in terms of years of life and health remaining, is not what it means today as longevity rises. They set a prospective old-age threshold at the age where average remaining life expectancy falls to a chosen value (commonly 15 years), and that threshold rises over time as people live longer. The POADR then counts people above this moving threshold relative to the working-age population below it. Because the threshold advances with longevity, the prospective ratio increases far more slowly — and can even fall — compared with the conventional ratio that fixes old age at 65. Sanderson and Scherbov's provocatively titled finding, that average remaining lifetimes can increase even as populations 'age,' reframed debates about the sustainability of aging societies. The measure is part of their broader characteristics-based approach to age.	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.