השוואת שיטות

	Population Momentum	תחזית אוכלוסייה בשיטת קוהורט-רכיב
תחום	דמוגרפיה	דמוגרפיה
משפחה	Process / pipeline	Process / pipeline
שנת המקור	1971	2001
הוגה השיטה	Nathan Keyfitz	Preston, Heuveline & Guillot
סוג	Measure of latent growth from age structure after fertility reaches replacement	Demographic projection pipeline
מקור מכונן	Keyfitz, N. (1971). On the momentum of population growth. Demography, 8(1), 71–80.	Preston, S. H., Heuveline, P., & Guillot, M. (2001). Demography: Measuring and Modeling Population Processes. Blackwell. ISBN: 978-1-557-86451-2
כינויים	Demographic Momentum, Momentum of Population Growth, Keyfitz Momentum	Cohort-Component Method, Component Method of Population Projection, Age-Sex-Specific Population Projection, Kohort-Bileşen Projeksiyonu
קשורות	3	3
תקציר	Population momentum is the tendency of a growing population to keep growing for decades even after fertility falls to the replacement level, simply because its age structure is heavily weighted toward young people who have yet to reach childbearing age. Introduced by Nathan Keyfitz in 1971, the momentum factor measures how much larger (or smaller) a population will ultimately become if fertility instantly drops to exact replacement. It explains why ending rapid population growth is not immediate: the built-in youthfulness of a fast-growing population carries growth forward long after birth rates stabilize.	Cohort-Component Projection is the standard demographic method for forecasting future population size and age-sex structure by explicitly tracking births, deaths, and migration for each age-sex cohort across discrete time steps. Systematically formalized in the textbook literature by Preston, Heuveline, and Guillot (2001), the method builds on foundational actuarial and demographic work dating to the early twentieth century and remains the workhorse technique used by national statistical offices and international organizations worldwide.