مقایسهٔ روش‌ها

	Lexis Diagram	Preston-Coale Method
حوزه	جمعیت‌شناسی	جمعیت‌شناسی
خانواده	Process / pipeline	Process / pipeline
سال پیدایش	1875	1982
پدیدآور	Wilhelm Lexis	Samuel H. Preston & Ansley J. Coale
نوع	Geometric bookkeeping device for demographic events on the age, period, and cohort axes	Death distribution method that reconstructs a population from its deaths to estimate registration completeness
منبع بنیادین	Preston, S. H., Heuveline, P., & Guillot, M. (2001). Demography: Measuring and Modeling Population Processes. Blackwell. ISBN: 9781557864512	Preston, S. H., & Coale, A. J. (1982). Age structure, growth, attrition, and accession: a new synthesis. Population Index, 48(2), 217–259.
نام‌های دیگر	Lexis surface, Age-period-cohort diagram, Lexis grid, Lexis Diyagramı	Synthetic extinct generations method, SEG method, Preston-Coale death distribution method, Preston-Coale Yöntemi
مرتبط	4	4
خلاصه	The Lexis diagram is a geometric bookkeeping device that places every demographic event in a two-dimensional grid of age against calendar time, so that each person's life traces a diagonal line and each cohort fans out as a band of parallel lifelines. Named after the German statistician Wilhelm Lexis, it is the foundational drawing of formal demography: it makes the otherwise confusing relationship between age, period, and birth cohort visible, and it tells the analyst exactly which deaths, births, and person-years belong together when a rate is computed.	The Preston-Coale method, also called the synthetic extinct generations method, estimates the completeness of death registration by rebuilding a population from the very deaths it records. Introduced by Samuel Preston and Ansley Coale in 1982, it uses the variable-r relations of a non-stable population to project each age group's future deaths forward, growth-adjust them, and accumulate them into the number of people who must currently be alive at each age. Comparing this implied population with the observed census count reveals what fraction of deaths the vital system actually captures.