VID Colloquium
Measurement of intergenerational replacement
Tomáš Sobotka, Wittgenstein Centre (IIASA, VID/ÖAW, WU)
Date: Wed, 4 July 2012, Time: 17:00 - 18:00
An important topic in demography is long-term equilibrium between fertility and mortality and hence intergenerational population replacement. Observed fertility is often compared to the “replacement level”, which in countries with low mortality equals 2.07 births per woman. However, this concept assumes a closed population with no migration. As migration has become a major component of change in most of the developed world, researchers have called for accommodating it into the standard tools of population analysis. New concepts and measures of intergenerational replacement have been proposed. Three aspects are presented: First, to clarify different concepts, birth replacement which relates the number of births in one generation to the next is distinguished from population replacement which relates the size of a cohort later in life to that of its parents. Second, the Net Birth Replacement Ratio and the Overall Replacement Ratio are used to analyse trends in birth and population replacement in the presence of migration in developed countries. Third, the concept of replacement fertility is reconsidered, and the levels of period fertility needed to assure birth and generational replacement in the presence of migration are computed for 26 countries. For most of them these redefined indicators of intergenerational replacement fall well below the threshold of two births per woman, giving a less dramatic perspective on the observed low fertility levels.
About the presenterTomáš Sobotka is a senior researcher at the Wittgenstein Centre (IIASA, VID/ÖAW, WU), Vienna Institute of Demography/Austrian Academy of Sciences. He holds a Ph.D. from the University of Groningen. The main focus of his research is on fertility and reproduction in low fertility countries, especially childlessness. He is a co-director of the Human Fertility Database (HFD). In 2011 he won an ERC Starting Grant with the project “Fertility, reproduction and population change in 21st century Europe (EURREP)".
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