Previous Colloquia:

From the Stork to Fertility Apps

19 July 2021

Ross Barker
Austrian Academy of Sciences


The market for smartphone apps tracking fertility has grown in recent years. These apps brand themselves as empowering their users to reach their reproductive goals, claiming to help achieve a pregnancy more easily than through conventional medical channels. This paper offers the first comprehensive quantification of fertility tracking app users. Using data collected from Google Play Store and Apple App Store, we calculate the most downloaded apps, and the global distribution of use. We use a log-log model fitted on the Google Play Store data to predict the Apple App Store number of installations. Our findings show that 74% of downloads are for just three of 28 apps. The majority of the reviews are left by users in North America, Northern Europe, and Australia; but it is noteworthy that downloads are also widespread in the Global South. Ongoing work aims to investigate the most discussed topics in the reviews.

About the presenter:

Ross Barker is a pre-doctoral research assistant in the Vienna Institute of Demography, jointly part of the Demography of Austria research group and the Family and Fertility research group, joining the BIRTH-LIFE project in September 2020. His work focuses on the intention to have a child, using survey data and web-based data. He intends him-self to find new sources of data to explore how the digital revolution is affecting the intention to have a child, and how increased use of mobile phone apps affects the ability to realise those intentions.

Video on Youtube


Covid-19, Social-Distancing and Lock-Downs in a simple Ramsey Economy: The role of networks

15 July 2021

Torben Klarl
University of Bremen


We develop a microfounded network-based SIS model where network connections vary between members. This model is embedded into a standard Ramsey Economy. We study the optimal lockdown policy for a planner who wants to control fatalities of the Covid-19 epidemic while minimizing consumption costs of the lock-down. We show that the optimal lock-down policy depends not only on the fraction of susceptible and infected persons but, importantly, on the average degree node of the network, which is a measure of social distancing. Not accounting for this would lead to biased policy recommendations and to welfare losses. In an extension, we expand our a setting where the agents do not fully take into account the effects of social distancing due to rational inattention motives.

About the presenter:

Torben Klarl currently works at the Department of Business and Eco-nomics at the University of Bre-men. He is also affliated with the BIGSSS (University of Bremen) and O’Neill School of Public and Environmental Affairs, Indiana University, Bloomington. Torben’s research focus is on various topics in applied macroeconomics such as sustainability, health, and innovation. More information can be found here.

Video on Youtube


MicroWELT – Microsimulation of Disaggregated National Transfer Accounts for the Comparative Study of Welfare State Regimes

18 May 2021

Martin Spielauer
Austrian Institute of Economic Research (WIFO)


This colloquium introduces MicroWELT, a microsimulation platform developed alongside the Horizon 2020 WELTRANSIM (Welfare Transfer Simulation) project. MicroWELT projects the interactions between welfare state regimes, welfare transfers and population ageing, accounting for educational change, life expectancy differentials and changing family patterns. Beyond the WELTRASNIM project, microWELT provides a versatile platform already used in various projects related to health, employment and care. MicroWELT integrates detailed socio-demographic projections with disaggregated National Transfer Accounts (NTAs). We study how disaggregating NTAs by family type and education affects NTA indicators and generational accounts. Our results show that indicators based on disaggregated data can give a very distinct picture of the economic effects of population ageing.

About the presenter:

Martin Spielauer is Senior Economist at the Austrian Institute of Economic Research (WIFO). He has 20 years of experience developing dynamic microsimulation models for the study of socio-demographic change, employment, health, social insurance, pensions and care in various countries. He is the lead developer of the microWELT model presented in this colloquium. As consultant of The World Bank, he leads the development of Dynamis-Pop, a portable model for population, education and health applications in developing countries.

Video on Youtube


Baby bust in the wake of the COVID-19 pandemic? First results from the new STFF data series

21 April 2021

Tomáš Sobotka & Kryštof Zeman
Wittgenstein Centre (IIASA, OeAW, University of Vienna)


Past evidence on fertility responses to external shocks, including economic recessions and the out-breaks of infectious diseases, show that people of-ten put their childbearing plans on hold in uncertaintimes. We study the most recent data on monthly birth trends to analyse the initial fertility responses to the outbreak of the COVID-19 pandemic. Ourresearch, based on new Short-Term Fertility Fluctu-ations (STFF) data series, embedded in the HumanFertility Database, shows the initial signs of the ex-pected “birth recession”. Monthly number of births in many countries have fallen sharply since October2020, often bringing about a clear reversal of theprevious trend. Across 17 countries with lower uc-tuations in births, births fell on average by 5.1% in November 2020, 6.5% in December 2020 and 8.9% in January 2021, compared with the same monthof the previous year. Spain sustained the sharpest drop in the number of births among the analysed countries, with the number of births plummeting by 20% in December 2020 and January 2021. Thecombined effect of rising mortality and falling birthrates is disrupting the balance of births and deaths in many countries, pushing natural population in-crease to record low levels.

About the presenters:

Tomáš Sobotkaleads the researchgroup Fertility and Family at theVienna Institute of Demography (OeAW). He also serves as an external lecturer at the Charles University in Prague and since 2021 as Editor of the Vienna Yearbook of Population Research. Kryštof Zeman is a research scientist with main focus on the Human Fertility Database project at the Department of Demography (Universityof Vienna). The presented work was created incollaboration with Aiva Jasilioniene, Ainhoa Alustiza Galarza, DmitriJdanov and László Németh from the Max Planck Institute for Demo-graphic Research (MPIDR).

Presentation Part I (Zeman)

Presentation Part II (Sobotka)

Born Once, Die Once: Lifetable Relationships for Fertility

9 March 2021

Annette Baudisch & Jesús-Adrián Alvarez
Interdisciplinary Centre on Population Dynamics


Everyone dies, once. This basic truth empowers formal mortality research. Similarly, everyone is born, once. This truth has not been fully exploited to benefit formal fertility research. Baudisch and Stott (2019) recently advanced the idea of an offspring population - yet unborn - awaiting the event of birth, introducing a novel survivorship concept for birth.
Formalizing the idea of ’birth survival’, here we define the underlying random variable and derive the central ’triplet’ of survival analysis functions - the hazard, density, and survival. We derive a straightforward framework to capture age-specific patterns of birth, analogous to classical life table functions. Based on age-specific birth counts, we construct a ’birth table’ and meaningful summary measures such as ’birth expectancy’ and associated measures of spread.
We advance a new framework to compare birth schedules across populations and to reveal macrolevel patterns and constraints. Our approach enables method transfer from mortality to fertility research, which can create an integrated framework to study birth and death for the same focal individual. Thereby, insights into the intertwined relationships between birth and death become possible. This, we envision, will open an entirely unexplored line of research.

About the presenter:

Professor Annette Baudisch is Vice Director at the Danish Centre for Demo-graphic Research | CDem within the Interdisciplinary Centre on Population Dynamics | CPop. As mathematician and demographer by training, her research advances concepts, theories and methods to study age-patterns of mortality and fertility. Changing the question of “why we age” to “why we age, but other species do not”, and creating the pace-shape framework of aging are her award-winning contributions to science.