News | September 29, 2016


On September 27, 2016, MPIDR PhD student Robert Stelter successfully defended his PhD at the Université catholique de Louvain, Belgium; and at the University of Rostock. In his work, Robert Stelter studied incentives to procreate from three different perspectives.

In the first part of his thesis, Robert Stelter discussed the so-called Unified Growth Theory, which scientists often use when seeking to explain the joint economic and demographic process population across the historical stages of human development. A sticking point in this theory is the demographic transition; i.e., the moment when the births and the mortality rates started to decline dramatically in the countries that are now industrialized. However, the role the rural exodus has played in this transition has hardly been studied. Together with Thomas Baudin from the Center for Demographic Research at the Université catholique de Louvain, Robert Stelter created a model that takes this exodus into account. They tested and calibrated their model using data from Denmark in order to show what would have happened if there had been no exodus. Their simulations generated the following picture: without the rural exodus, the transition to a low fertility rate would have happened even earlier in the cities, and birth rates would have been much lower; whereas in the countryside fertility would have been higher. Robert Stelter was therefore able to show with his modeling that the exodus played a central role in the overall decline in birth rates.

The demographic transition has led to significant shifts in the age structure. In the second part of his thesis, Robert Stelter investigated the possible over-aging of the populations of industrialized countries. In another theoretical model, he showed what the optimal age structures of a population might look like, and what policy measures might be taken to move toward achieving this optimal structure.

In the third part of his thesis, Robert Stelter relied upon both a theoretical model and empirical data, including data from the Socio-Economic Panel (SOEP), which provides information about income, employment, education, and health. He used these data to examine the question of whether there are differences in the fertility levels of women who have statutory health insurance coverage and women who have private health insurance coverage. In his calculations, he took into account socioeconomic factors such as age, education, and income. When these factors were controlled for, the results indicate that women who are privately insured have more children on average than women with statutory health insurance coverage. Among the possible causes are, for example, that the privately insured adults who are of childbearing age have relatively low health insurance premiums, and that this smaller financial burden is an incentive for them to have children. Another reason could be that the privately insured receive better medical care.