Francisco Villavicencio

The Dynamics of Son Preference, Technology Diffusion, and Fertility Decline Underlying Distorted Sex Ratios at Birth: A Simulation Approach

We present a micro-founded simulation model that formalizes the “ready, willing, and able” framework, originally used to explain historical fertility decline, to the practice of prenatal sex selection. The model generates sex ratio at birth (SRB) distortions from the bottom up and attempts to quantify plausible levels, trends, and interactions of son preference, technology diffusion, and fertility decline that underpin SRB trajectories at the macro level. Calibrating our model for South Korea, we show how even as the proportion with a preference for sons was declining, SRB distortions emerged due to rapid diffusion of prenatal sex determination technology combined with small but growing propensities to abort at low birth parities. Simulations reveal that relatively low levels of son preference (about 20 % to 30 % wanting one son) can result in skewed SRB levels if technology diffuses early and steadily, and if fertility falls rapidly to encourage sex-selective abortion at low parities. Model sensitivity analysis highlights how the shape of sex ratio trajectories is particularly sensitive to the timing and speed of prenatal sex-determination technology diffusion. The maximum SRB levels reached in a population are influenced by how the readiness to abort rises as a function of the fertility decline.

Reconstructing Lifespans Through Historical Marriage Records of Barcelona from the Sixteenth and Seventeenth Centuries

This chapter presents a methodology for reconstructing the lifespan of individuals through a nominal record linkage procedure using historical marriage records of Barcelona from the sixteenth and seventeenth centuries. The data are extracted from the Barcelona Historical Marriage Database (BHMD), a unique source that contains information about more than 600,000 marriages celebrated in both urban and rural parishes of the Barcelona area from over 450 years (1451–1905). We discuss the main characteristics of the database, the standardisation of the nominal information, the marriage linkage procedure and the reconstruction of the lifespans. Finally, we briefly introduce an application of Bayesian models to study adult mortality on the basis of the reconstructed lifespans.

A unified framework of demographic time

Demographic thought and practice is largely conditioned by the Lexis diagram, a two-dimensional graphical representation of the identity between age, period, and birth cohort. This relationship does not account for remaining years of life, total length of life, or time of death, whose use in demographic research is both underrepresented and incompletely situated. We describe an identity between these six demographic time measures and describe the sub-identities and diagrams that pertain to this identity. We provide an application of this framework to the measurement of late-life morbidity prevalence. We generalize these relationships to higher order identities derived from an arbitrary number of events in calendar time. Our examples are based on classic human demography, but the concepts we present can reveal patterns and relationships in any event history data, and contribute to the study of human or non-human population dynamics measured on any scale of calendar time.

Feedback Mechanisms in the Postponement of Fertility in Spain

In this chapter we describe the process of fertility postponement initiated in Spain in the mid-1970s using a dynamic model that considers the interaction of four main factors. Rising economic uncertainty and the expansion of higher education provide the original impulse which is later amplified by the feedback generated via social interaction as young men and women start imitating the behavior of their peers and friends. As the pressure to conform to an early family formation standard is reduced, the postponement process gains momentum. This multiplier effect explains a substantial part of the observed trend, but its pace and extent also depend on the resistance exerted by social norms. Our model tries to capture the dynamic mechanism by which norms shape behaviors and behaviors shape norms, in a process of mutual dependence. This feedback loop between individual actions and aggregated outcomes allows us to bridge the micro and macro levels of analysis and it proves to be a key element in the explanation of the massive and ongoing transformation of fertility patterns in Spain in the last decades.