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| Net Reproduction Rate (NRR) in China, Europe, USA and India: 1950-2100 | |||||||
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Source: United Nations,
Department of Economic and Social Affairs, Population
Division (2011): World Population Prospects, the 2010 Revision. New York. See:
www.unpopulation.org |
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The Net Reproduction Rate (NRR) is a synthetic demographic rate that measures the average number of daughters per woman who survive to average reproductive age. Essentially, the Net Reproduction Rate measures, to what extent one generation is replaced by the next generation - taking into account both the level of (period) fertility and mortality. A Net Reproduction Rate of 1.0 indicates that one generation is exactly replaced by the next generation. A NRR of 0.7 indicates that one generation is replaced by only 70% - the population is intrinsically declining 30% from generation to generation. The Net Reproduction Rate is probably the most accurate (period) measure of the actual demographic situation in a particular population. It eliminates age structure effects, which can seriously distort the rates of population growth or decline, as well as the birth and death rates. The NRR shows, how a population would change with the current vital rates. It is often an "early warning sign". The NRR illustrates what is actually going on in a population by analytically removing momentum effects and migration flows. |
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Today, in Europe and - surprisingly - in China the Net Reproduction Rate is far below 1.0, which indicates that both Europe and China have a population that is intrinsically shrinking from births and deaths. Only age-structure effect in the case of China and massive immigration in the case of Europe (and the United States of America) prevent the actual decline of these populations between generations. |
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The United States of America has been intrinsically shrinking since the period of 1970-1975 (of course this was compensated by large immigration flows, so that the population was actually increasing); Europe has been intrinsically declining between generations since the period of 1975-1980 and China fell below a NRR level of 1.0 in the period of 1990-1995. |
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India, on the other hand, still has a Net Reproduction Rate of about 1.1 - indicating a 10% intrinsic increase of the population between generations. According to the United Nations World Population Prospects, India will only fall below a NRR level of 1.0 in the period of 2025-2030. |
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| This section was updated on 10 June 2011. | |||||||
