We are engaging in the theoretical and empirical analysis of population processes and structures, an understanding of which is a cornerstone to all research on population economics.
Currently we are undertaking work within the following areas:
Elderly People Ever-lived
The question of how many people have ever lived has been discussed extensively in the demographic literature and it is one of the most frequently asked in the literature. In a recent study, Joel E. Cohen (Demographic Research, 2014) followed up this earlier research and showed that the fraction of people ever born who are currently alive is increasing. Following a similar intuition, Fred Pearce (The Economist, 2014) argued that half of all people who have ever reached the age 65 are alive today. If confirmed such a finding would imply extremely rapid population ageing driven by the recent declines in fertility and the progressive increase in longevity.
The aim of this project is to extend the analysis made by Cohen and investigate the fraction of people above a specific age threshold (y) alive in year (T) to the population that ever was alive and reached this age threshold, which we denote by (π(y,T)).
Our objectives are
- to analyse the main properties of π(y,T) by age and over time using actual demographic data
- to study the feasible values of π(y,T) in order to understand the pace of population aging
- to theoretically study π(y,T) for different formal population models
The analysis of this fraction will not only extend the methodology but also yield a new view on the pace of population ageing over time.
Microsimulation of Union Dynamics and Fertility
Micro-level relationships between union formation or dissolution and childbearing have implications for macro-level fertility that have been thoroughly examined only since very recently. On the one hand, union dissolution reduces the opportunities for conceiving and bearing children. At the same time, it produces a pool of persons who may enter new partnerships and have additional children in stepfamilies. Indeed, it has been shown that the incremental risk of childbearing is much greater when all of a woman’s children were with previous partners, i.e. when the re-partnered couple has no shared children. Because first-time parents are highly likely to have two children together, new partnerships are particularly significant for third and fourth births. Moreover, union instability may lead to a delay of family formation, as many women and men are unable, or unwilling, to form a lasting union at younger ages, which is often seen as a precondition for parenthood. The postponement of childbearing induced by union instability may not only lead to a lower number of children but also to an increase in permanent involuntary childlessness. It is the balance of these opposing forces that influences not only the number of children per woman but also the family setting that they are born into. However, the results may differ across countries according to the particular socio-economic and cultural setting, e.g. the extent to which re-partnering and fertility outside the first marital union are accepted and diffused or banned as undesirable.
We develop a microsimulation model in order to investigate the interrelationships between partnership and childbearing and how they have changed among recent birth cohorts. In particular, we estimate hazard regression models of birth and union events for women born in the 1940s to the mid-1990s within selected European countries, the results of which will serve as parameters to our microsimulation model. The microsimulation generates hypothetical populations of women with different union and childbearing histories for all cohorts, allowing us to trace the evolution of family configurations over time and, thereby, to produce comparative estimates of completed fertility that could not be generated by observations of older cohorts.
We use the microsimulation model to study various aspects of the change in European partnership and fertility behaviour over the recent decades. First, we assess the impact of union instability on fertility in different country contexts, particularly with regard to differences in the spread of cohabitation, re-partnering and multi-partner fertility. Second, does the postponement of childbearing, induced by prolonged education, union instability etc. result in higher prevalence of late fertility in first/second unions, lower family size and/or in more childlessness? Moreover, do these effects vary by educational group? More specifically, do educational gradients observed for the single childbearing and partnership transitions accumulate or do they offset each other over the family life course? Finally, we aim to assess how childhood experiences and parental resources affect family structure through the mechanisms of childbearing and partnership and whether education is able to mediate the outcomes for individuals from disadvantaged backgrounds.
Parts of the analysis are being supported by the European Union within the framework of the FamiliesAndSocieties (FP7-SSH-2012-1, GA No. 320116) project. This research is carried out in collaboration with Eva Beaujouan, Martin Spielauer, Paola Di Giulio, and Ann Berrington.