方法对比

	Demographic Balancing Equation	Net Migration Rate
领域	人口学	人口学
方法族	Process / pipeline	Process / pipeline
起源年份	1976	1976
提出者	Classical demographic accounting identity	Classical vital-statistics measure (formalized by Shryock & Siegel)
类型	Population accounting identity for change over a period	Rate of net population change due to migration per unit population
开创性文献	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
别名	Balancing Equation of Population Change, Population Accounting Equation, Components of Population Change Identity	Net Migration Ratio, Crude Net Migration Rate, Net Migration per 1000
相关	4	4
摘要	The demographic balancing equation is the fundamental accounting identity of population change: a population at the end of a period equals its size at the start, plus births, minus deaths, plus in-migrants, minus out-migrants. It is the bookkeeping rule that ties together all the components of population dynamics and guarantees internal consistency in population estimates and projections. Because it is an exact identity, it also serves as a powerful estimation tool — any single unknown component, most often net migration, can be recovered as the residual once the others are known.	The net migration rate expresses the net effect of migration on a population's size as a rate: net migration — in-migrants minus out-migrants over a period — divided by the population at risk, conventionally stated per 1000 people. It is the migration counterpart to the rate of natural increase and a standard component of population accounting. Because directional migration flows are often poorly recorded, net migration is frequently not counted directly but estimated as a residual from the demographic balancing equation or by comparing surviving cohorts across two censuses.