Models can also be helpful in social studies. For example, one can simulate and discuss different models for the demographic development in the Federal Republic of Germany or all over the world. As a suggestion, a very simple population model for the Federal Republic is presented here. The rough numerical values can be replaced by current figures.
At present the population of a country is about 80 million. It is roughly increased by the birth rate and reduced by the number of deaths. The number of births as well as the number of deaths certainly depends on the population size, so that the following simple semantical model results:
Increase is proportional to population
Decrease is proportional to population
The proportionality factors are certainly different. Assume a birth factor of 0.0095 and a death factor of 0.0117. How large will the population be in 2040?
The model can now be extended as required, e.g. by a constant immigration rate, a division into different age groups with different rates of change. These extensions allow you to obtain an increasingly accurate model for real population growth.