So sánh phương pháp

	Prospective Old-Age Dependency Ratio	Characteristics Approach to Population Aging
Lĩnh vực	Social Gerontology	Social Gerontology
Họ	Survival analysis	Survival analysis
Năm ra đời	2005	2013
Người khởi xướng	Warren C. Sanderson & Sergei Scherbov	Warren C. Sanderson and Sergei Scherbov
Loại	Demographic ratio using a moving, longevity-based old-age threshold	Framework for measuring population aging by characteristics rather than chronological age
Công trình gốc	Sanderson, W. C., & Scherbov, S. (2005). Average remaining lifetimes can increase as human populations age. Nature, 435(7043), 811-813.	Sanderson, W. C., & Scherbov, S. (2013). The characteristics approach to the measurement of population aging. Population and Development Review, 39(4), 673-685.
Tên gọi khác	POADR, Prospective Dependency Ratio, Sanderson-Scherbov Dependency Ratio, Remaining-Life-Expectancy Old-Age Ratio	Characteristics-Based Aging Measures, Sanderson-Scherbov Characteristics Approach, Alpha-Age Approach, Equivalent-Age Method
Liên quan	3	3
Tóm tắt	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 characteristics approach reconceptualizes what it means to be 'old' by measuring age through people's characteristics rather than the number of years since birth. Developed by Warren Sanderson and Sergei Scherbov and set out comprehensively in their 2013 Population and Development Review article, it responds to the fact that conventional aging measures treat a fixed chronological age, such as 65, as a permanent marker of old age even though people at 65 today are healthier and longer-lived than their counterparts decades ago. The core idea is that many relevant attributes, such as remaining life expectancy, health, cognitive function, and disability, vary with both age and time, so old age should be defined by reaching a given level of such a characteristic rather than a fixed birthday. The approach computes equivalent or 'alpha' ages, the ages at which a characteristic takes a chosen reference value, and uses them to build characteristic-based aging indicators. Comparing these with conventional measures often shows that populations are aging more slowly, or even getting younger on some dimensions, than chronological measures suggest. The framework has reshaped how demographers assess the consequences of population aging.