Coordinated population projection by the Federal Statistical Office

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The Federal Statistical Office carries out “coordinated” population projections for the Federation and the Länder together with the statistical offices of the 16 Länder . A “coordinated” forecast provides results that are comparable to one another and based on agreed assumptions and the same calculation methods.

Population projections include the following current figures: Population figures of the federal states according to the current update of the respective state office. In part, assumptions about the “migration gains” from immigration and emigration as well as relocations between the federal states ( internal migration ) as well as about the “excess deaths ” or “losses” ( births minus deaths) since the last census . This is necessary because the population registers never quite reflect the real numbers of people in one place.

Population projections also include calculations based on assumptions that are based on the respective best numbers for “migration gains” and “death surpluses”, but of course carry an uncertainty factor as a forecast value. The model does not have any computational uncertainty because the value is clearly shown as an assumption. Should z. If, for example, the cancer mortality of younger women change in the future, this would be easy to identify and take into account as an error rate in the forecast values.

Model character of statistical representations

The long-term, coordinated population projections of the Federal Statistical Office ( Wiesbaden ; 1st to 13th coordinated population projection ), which have been continuously updated over the past few decades, are of a model nature . With different development conditions defined in advance within the realm of the possible, they model different models of how the numbers will develop when these development conditions occur. This means there is a lower and an upper variant. In 2015, 8 variants were calculated.

Difference between model and forecast

The model statements are not predictions , but are based on the current age structure and implement the assumptions precisely described there. The calculation not only provides results for the entire Federal Republic of Germany , but also for the population development in the German federal states . It assumes the same calculation methods. However, all unpredictable events that would influence the development cannot be the subject of such models (" ceteris paribus clausel "). For the past there is no real or hypothetical projection of the population for 50 years that would be confirmed by reality.

Risk of political instrumentalization and manipulation

When using statistics in a political context, there is a risk of instrumentalization and manipulation. The model-like assumptions of the statistical calculation are interpreted as unchangeable facts and as the only criteria for assessing facts, which cannot be the content and intention of the statistics. The political responsibility for shaping reality is thus denied and the proposed measures are presented as an adaptation to practical constraints without alternatives.

The implementation

The population projection is carried out taking into account several variables: assumptions on the development of migrations across the respective national border, assumptions on the development of births and life expectancy.

  • Immigration from abroad was taken into account in two variants in this calculation: Variant 1 with a long-term annual immigration gain of 100,000 people and variant 2 with a balance of 200,000 people. In addition, emigration and relocations between the federal states must be taken into account as a gain or loss for the countries concerned. For the past there are values ​​broken down according to age and gender. These are updated in the future, coordinated by the statistical offices of the federal states. This is another possible margin of error for population projections. Immigration as a factor in future changes in the population can largely be read off mathematically as immigration surpluses for the respective years. In variant 1, these will add up to a volume of 5.8 million people in the period from 2000 to 2050 (around 100,000 annually). According to variant 2, a total of 10.2 million (around 200,000 annually) will immigrate. The age of the newcomers varies, the main weight being between the ages of 18 and 23. Accordingly, the numbers of the individual cohorts increase somewhat differently even after the year of birth. For the population projection, it is assumed that there will be a long-term birth deficit due to the increase in life expectancy by around six years by 2050 and the reduced number of births.
  • The birth rate in the former federal territory in Germany remains at 1.4 children (alignment also in the five new federal states of the initially significantly lower birth rate up to around 2005 with that in western Germany). The average number of children per woman is broken down again according to the age of the women, family types and regions. For a steady population development, a statistical number of children of 2.1 children would be required as an average for every woman in the course of her life. Individual family planning leads to different results, which, however, can be roughly estimated in total. The number 1.4 has proven to be a relatively stable figure for the average number of children among women in Germany since the “ pill break ”. In other variants, a slight increase or decrease in this indicator is taken into account.
  • The life expectancy increases - in decades - next: For newborns meanwhile assumptions are 78.1 years for boys and 84.5 years for girls. The further life expectancy for 60-year-olds is 21.6 years (+ 2.7 years) for men and a further 26.7 years (+ 3.5 years) for women. The number of deaths observed so far will be divided up for future calculations according to previous experience. If life expectancy is expected to increase, a “sliding” adjustment of the values ​​must be made in the intervening years.

All further calculation steps can now be imagined as a chain of individual calculations for each living age group. For example, 450,000 men and 420,000 women aged 25 and over lived in Germany in 2005 from those born in 1980. These men and women can still be subdivided according to marital status and nationality. Statistics knows these numbers as starting values ​​and can now calculate in 25 fictitious annual steps by 2030 how these subgroups and the entire year will change, primarily due to births, marriages, immigration, divorces, emigration and deaths. It is expected to decrease slightly in number. In a further 20 fictitious annual steps, the year 2050 would have been reached and those still alive in this year would have reached the age of 70 in the population projection. The natural decline in the number of this age group would have started in the last calculated decade of life, because the old age mortality of men is already on the rise.

The 2005 vintage should be considered as a further example. The number of children born this year can already be estimated relatively precisely in 2005 compared with previous years. How will this year of around 330,000 boys and 310,000 girls change in the future? 25 fictitious annual steps must also be calculated by 2030. The children will probably grow to be a few thousand more people by then, because immigrant foreigners bring children with them who were also born in 2005. Some of these young people will still be singles, but many will already contribute to the reproduction of future generations in communities such as marriage. Few will have died from illness or unnatural causes of death. All of this flows into the population forecast for this year. If a further 20 fictitious annual steps are calculated, the year 2050 would also have been reached and most of the living in this year would have reached the age of 45 in the forecast. The possible number of children may have consequences for the calculations of the following years (or no children from unborn parents).

For the entire population projection, all values ​​must be added up in this way per year for all years.

The accuracy of the calculations

In statistics, it is usually also calculated how exactly a model can actually apply ( error rate ). The possible deviation can be estimated by calculation ...

In contrast to this, one tries to counteract the possible deviation with these methods by calculating variants with differently high, but openly indicated acceptance digits (calculation variables). The variants are laid out in such a way that, based on current knowledge, they slightly exceed or fall below the future development. I.e. the actual development will most likely lie within the range of the variants. In the case of recognizable changes in individual computational variables, it will therefore be easy to read in which direction the actual development will run within the range of variants.

The history of the models

The 1st to 12th coordinated population projection ....

Foundation of the Federal Institute for Population Research in 1973

  1. 1966 - 1st coordinated population projection up to 2000
  2. 1968 - 2nd coordinated population projection up to 1990
  3. 1970 - 3rd coordinated population projection up to 1985 and up to 2000
  4. 1972 - 4th coordinated population projection up to 1985
  5. 1975 - 5th coordinated population projection up to 1990
  6. - 6th coordinated population projection - gap year
  7. 1992 - 7th coordinated population projection until 2030
  8. 1994 - 8th coordinated population projection until 2040
  9. 2000 - 9th coordinated population projection
  10. 2003 -10. coordinated population projection up to 2050
  11. 2006 -11. coordinated population projection up to 2050
  12. 2009 -12. coordinated population projection up to 2060

Use in a political environment

In the Bundestag between 1992 (12th edition) and 2002 there was a commission of inquiry “ Demographic Change - Challenges of our aging society for the individual and politics ”. This commission should prepare and evaluate the figures for the Bundestag, which social, economic and social effects result from them for all generations. It should (and has in the meantime) determine the foreseeable need for action and give recommendations for political decisions.

BT-Drucksache 14/8800 of March 28, 2002 contains the final report of the Enquête Commission in the 14th electoral term.

See also

literature

  • Mueller, Ulrich, B. Nauck et al. A. Diekmann (ed.): Handbook of Demography . Vol. 1: Models and Methods . Berlin / Heidelberg: Springer-Verlag 2000, ISBN 3-540-66106-9 ; Vol. 2: Applications . Berlin / Heidelberg: Springer-Verlag 2000, ISBN 3-540-66108-5 .
  • Mueller, Ulrich: Demographic statistics and population dynamics. Methods and models of demography for economists, social scientists, bioscientists and medical professionals . Berlin, New York: de Gruyter 1993, ISBN 3-11-013870-0 .
  • Höhn, Charlotte 1986: Official population forecast since 1925 - a brief history of policy advice and the demographic climate. In: Hanau, Klaus; Hujer, Reinhard; Neubauer, Werner (ed.): Economic and social statistics. Empirical bases of political decisions. Heinz Grohmann on his 65th birthday. Göttingen: 209-231.

Web links

Wiktionary: Demography  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ See e.g. B. Ingeborg Vorndran: Census test - procedure and results of household generation . In: Economy and Statistics, 2004, Federal Statistical Office, Wiesbaden. (This describes the efforts to infer real living and living conditions from registration data.)
  2. ^ Gerd Bosbach with Jens Jürgen Korff : Lies with Numbers. How we are manipulated with statistics. Heyne, Munich 2011, ISBN 978-3-453-17391-0 ; ibid. 2012, ISBN 978-3-453-60248-9 . Lies with numbers , blog about the book; Lies with numbers - the authors Bosbach and Korff in conversation with Carsten Schmidt, website of Lexikus Verlag, May 8, 201
  3. ↑ Jürgen Duschk, Julia Weinmann and others: Life in Germany. Households, Families and Health - Results of the Microcensus 2005 . Federal Statistical Office, Wiesbaden 2005
  4. ↑ Much of the information can be found in the compilations by Stührenberg, Lutz / Töpken, Matthias 1996: Prognostik im Tonelfeld von Creativity and Systematik Integration of the scenario technology into a qualitative forecast model using the example of population development in the Federal Republic of Germany. Frankfurt am Main. P. 26ff. as well as in a compilation in "Wirtschaft und Statistik" 4/1986, pp. 255–260.
  5. ↑ Federal Statistical Office (2006). Population of Germany until 2050 - 11th coordinated population projection
  6. ↑ Federal Statistical Office (2009). Population of Germany until 2060 - 12th coordinated population projection
  7. ↑ Printed matter 14/8800 (PDF) German Bundestag. March 28, 2002. Accessed June 23, 2019.