Demography is the study of populations but populations consist of humans who are embedded in their social context. When humans take decisions they are exposed to examples, expectations, and opportunities provided by their peers. Therefore, raising demography from description to exploration requires to study social effects. Social effects are divided into social learning, which is based on the exchange of knowledge and information, and social influence arising from the desire to avoid conflict within social groups and the threat of group disintegration. Peers provide information that enlarges the set of alternatives, show the consequences of decisions and affect individual preferences by means of social-influence effects and conformity pressures.

Agent-based models (ABMs) are computational models for simulating the actions and interactions of agents, allowing us to include social interactions and social effects in the individual decisionmaking processes. Agents are autonomous and interdependent, they follow simple rules and they are adaptive and backward–looking. Typically an agent represents an individual but it can also be a couple, a family, a company, or an agency. In demography ABMs are mostly used to explain patterns observed at the macro level as a result of decisions taken at the micro level. The research group at VID applies ABMs to investigate fertility transitions, marriage and union formation, the emergence of social norms, the influence of social effects on the effectiveness of family policies, and the interplay of changing gender roles and fertility.


Family Policies

Thomas Fent, Alexia Prskawetz, Bernhard Rengs,

In this project we investigate the effectiveness of family policies in the context of the social structure of a population. We use an agent-based model to analyse the impact of fixed and proportional family policies on intended fertility, on the realisation of intended fertility and on the resulting completed cohort fertility. In particular, we investigate whether the structure of a society represented by parameters specifying the social network and social effects has the potential to alter the role of family policies. In our modelling framework, individuals are characterised by their sociodemographic characteristics age, household budget, parity, the number of dependent children and intended fertility. The agents are closely linked to a set of other agents with whom they discuss their fertility intentions and the realisation of their plans. We refer to this group as the agent’s social network. The whole agent population constitutes the society. The agents are not directly linked to those agents who do not belong to their social network, but any agent may indirectly influence any other agent via intermediaries. The above-mentioned characteristics, as well as family policies and social effects, transmitted via the social network, have an impact on the agents’ fertility intentions and behaviour. The model allows us to carry out experiments to test various combinations of childcare benefits and combine them with different assumptions regarding the underlying social structure.

The crucial features of our model are the interactions between family policies and social structure, the agents' heterogeneity and the structure and influence of the social network. This modelling framework allows us to disentangle the direct effect (the alleviation of resource constraints) from the indirect effect (the diffusion of fertility intentions via social ties) of family policies. Our results indicate that family policies have a positive and significant impact on fertility. In addition, the specific characteristics of the social network and social effects do not only relate to fertility, but also influence the effectiveness of family policies. Family policies can only be successful if they are designed to take into account the characteristics of the society in which they are implemented.


Gender Relations and Fertility

Thomas Fent, Bernhard Rengs

In the traditional view, progress in economic and societal development results in ever lower fertility. During the last decade this trend has changed and several highly developed countries experienced a recovery of fertility. Scholars have provided various explanations for this effect. A purely statistical approach attributes the reversal to the end or decrease of the tempo effect due to a slower increase in mean age at birth while more causal approaches relate it to increases in human development, further progress in the second demographic transition or to the spread of more progressive gender roles at the individual or household level with advancements of gender equity at the societal level.

Recent literature on the interplay between gender roles and fertility confirms that the relationship of the two is not at all straightforward. The classical view of further progress of the female revolution leading to a monotonous decrease in fertility does not hold anymore. In its advanced stages, the revolution will produce novel family norms that are in better harmony with individual child and partnership preferences. Consequently, there may be a U-shaped relationship of the total fertility rate TFR vs. female revolution. The diffusion from traditional to egalitarian gender behaviour and its impact on fertility dynamics is a complex process involving several interdependencies. Further progress of egalitarian values may induce institutional changes, e.g. in terms of better childcare arrangements or the evolution of social norms towards working mothers that facilitate the compatibility of parenting and pursuing a professional career.

Our model focuses on the relationship between fertility and gender roles and investigates a heterogeneous population of agents who derive utility from consumption and from meeting their individual fertility intentions. Policymakers have the possibility to favour more progressive gender roles. We distinguish between gender equality and gender equity. Gender equality, on the one hand, measures how men and women differ in their outcomes with respect to income, education, labour market etc., while gender equity, on the other hand, addresses the perception of fairness and opportunities. Whereas empirical papers often apply measures of gender equality due to better data availability, in our simulation model we explicitly rely on gender equity because we consider it to be more relevant in the context of fertility.

Simulation results show that the model does indeed lead to the expected social effects for a wide range of parameter values. Higher governmental subsidies lead to higher gender equity in the artificial society. In turn, higher gender equity essentially results in lower levels of fertility but very advanced societies experience a slight upturn. Thus, our model confirms the idea of a U-shaped relation between gender equity and fertility. Moreover, higher levels of gender equity lead to more consumption and to higher utility which we use as a proxy for well-being and happiness.

This work is part of the EU FP7 project “Families and Societies”:


Gender Equality, Fertility and Education

Gustav Feichtinger, Alexia Prskawetz

In general, the spreading of gender egalitarianism has often been associated with a decline in fertility. However, recently a rebound in fertility has been observed in several industrialised countries. A possible explanation of this trend may be the spread of egalitarian values that induced institutional changes—such as expansion of childcare facilities and father leave—and also changes in norms and values—such as gender equity in the distribution of domestic work—that foster the combination of parenthood and an egalitarian lifestyle.

In the present project we analyse diffusion models to study different mechanisms which might lead to a recovery of fertility rates. It is shown that the long-run development of the total fertility within a population not only depends on key parameters such as the pace of diffusion of egalitarianism and the extent to which social interactions affect the egalitarians' birth rates, but also on the initial number of traditionalists and egalitarians.

We show that a recovery of fertility might either relate to the success or the failure of egalitarianism within the society. We find that a time lag between the change of family ideals and the support of the egalitarian lifestyle within a society strongly influences the extent and the duration of the decline of fertility as well as the subsequent recovery.