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	Net Reproduction Rate	Gross Reproduction Rate
分野	人口学	人口学
系統	Process / pipeline	Process / pipeline
提唱年	2001	1928
提唱者	Richard Böckh and Robert Kuczynski (formalized in Preston, Heuveline & Guillot)	Richard Böckh (concept) and Robert R. Kuczynski (popularization)
種類	Period measure of generational replacement combining fertility and mortality	Single-sex summary fertility measure counting daughters per woman
原典	Preston, S. H., Heuveline, P., & Guillot, M. (2001). Demography: Measuring and Modeling Population Processes. Blackwell. ISBN: 9781557864512	Preston, S. H., Heuveline, P., & Guillot, M. (2001). Demography: Measuring and Modeling Population Processes. Blackwell. ISBN: 9781557864512
別名	NRR, Net reproduction ratio, Net reproductive rate, Net Üreme Hızı	GRR, Gross reproductive rate, Daughters per woman (without mortality), Brüt Üreme Hızı
関連	4	4
概要	The net reproduction rate (NRR) is the demographic measure of generational replacement: the average number of daughters a woman would bear who survive to the age their mother was when she bore them, given the period's age-specific fertility rates and female mortality. By combining fertility with survival, the NRR answers the fundamental question of whether a population is replacing itself — an NRR of one means each generation of women exactly reproduces the next, below one signals long-run decline, and above one signals growth.	The gross reproduction rate is the average number of daughters a woman would bear over her lifetime if she experienced a given set of age-specific fertility rates and survived through all her childbearing years. It is a single-sex reproduction measure: by counting only daughters, it tracks how a generation of women replaces itself, ignoring the mortality that would thin the next generation. As such it sits between the total fertility rate, which counts all children, and the net reproduction rate, which discounts daughters for the chance of dying before they themselves reproduce.