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	Pollard Decomposition	生命表解析
分野	人口学	人口学
系統	Process / pipeline	Survival analysis
提唱年	1982	1984
提唱者	John H. Pollard	Demographic/actuarial tradition; Chiang
種類	Age-specific decomposition of a difference in life expectancy	Age-structured mortality estimator
原典	Pollard, J. H. (1982). The expectation of life and its relationship to mortality. Journal of the Institute of Actuaries, 109(2), 225–240.	Chiang, C. L. (1984). The Life Table and Its Applications. Robert E. Krieger Publishing. ISBN: 978-0-89874-565-2
別名	Pollard's Method, Pollard Life Expectancy Decomposition, Continuous Age Decomposition of Life Expectancy	Mortality Table, Actuarial Table, Survival Table, Yaşam Tablosu
関連	4	3
概要	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.	A life table is a systematic, age-structured summary of the mortality experience of a population. It traces a hypothetical cohort of births — conventionally 100,000 — through successive age intervals, recording how many survive, how many die, and how many person-years are lived at each interval. The method was formalized in its modern probabilistic form by Chiang (1984), synthesizing centuries of actuarial and demographic practice into a rigorous statistical framework applicable to human and biological populations alike.