قارن الطرق

	Life Expectancy Decomposition	Pollard Decomposition
المجال	Social Epidemiology	علم السكان
العائلة	Process / pipeline	Process / pipeline
سنة النشأة	1984	1982
صاحب الطريقة	Eduardo E. Arriaga; John H. Pollard	John H. Pollard
النوع	Demographic decomposition pipeline for differences in a summary measure	Age-specific decomposition of a difference in life expectancy
المصدر التأسيسي	Arriaga, E. E. (1984). Measuring and explaining the change in life expectancies. Demography, 21(1), 83-96.	Pollard, J. H. (1982). The expectation of life and its relationship to mortality. Journal of the Institute of Actuaries, 109(2), 225–240.
الأسماء البديلة	Life Expectancy Decomposition Methods, Decomposition of Changes in Life Expectancy, Age and Cause Decomposition of Life Expectancy, Stepwise Life Expectancy Decomposition	Pollard's Method, Pollard Life Expectancy Decomposition, Continuous Age Decomposition of Life Expectancy
ذات صلة	4	4
الملخص	Life-expectancy decomposition answers a question that a single number cannot: when life expectancy rises over time, or differs between two populations, exactly which ages and which causes of death are responsible? The family of methods takes two life tables and splits their gap in e0 (or ex at any age) into additive contributions from mortality differences in each age interval, with the contributions summing exactly to the total gap. Eduardo Arriaga's 1984 stepwise discrete method became the field standard because it is exact, intuitive, and easy to extend to a cause-of-death breakdown, separating a 'direct' effect of changed survival within an interval from an 'indirect plus interaction' effect that the change propagates to later ages. John Pollard's continuous formulation expresses the same decomposition as an integral of age-specific mortality differences weighted by their leverage on life expectancy, providing the theoretical underpinning and a cross-check. This page treats the general decomposition pipeline; the dedicated Arriaga and Pollard pages cover each estimator in depth.	Pollard's decomposition breaks a difference in life expectancy between two populations into additive contributions from each age, showing exactly how much of the gap is due to mortality differences at infancy, in midlife, or in old age. John Pollard derived a continuous-age formula expressing the life-expectancy difference as an integral of the age-specific mortality-rate difference weighted by life-table functions. Because the contributions sum exactly to the total gap and can be further split by cause of death, the method is a standard tool for explaining why one population outlives another.