Volume 40 - Article 10 | Pages 261–278  

Identifying interaction effects using random fertility shocks

By Rannveig Hart, Sara Cools

Abstract

Background: Fertility interaction effects in social networks increasingly attracts the interest of demographers. While these theories propose a causal mechanism, they are rarely put to test in a plausibly causal statistical design.

Objective: We aim to differentiate network effects from selection by using an instrumental variable (IV) approach to achieve exogenous variation in fertility. We use interaction effects between siblings as an empirical example.

Methods: We draw data from Norwegian administrative registers (N ∼ 170,000 men and women). We use twin births and children’s sex composition as random fertility shocks (IVs), generating exogenous variation in third births.

Results: In our full study sample, we find no significant effects on ego’s fertility of random shocks to the propensity to have three children. Subgroup analysis by sex and parity indicates positive effects for firstborn women when the sibling’s birth is intended (as captured by the same-sex instrument). We find no evidence that similarity strengthens interaction effects.

Conclusions: The study contributes to the literature by testing long-standing hypotheses of fertility interaction effects in a plausibly causal design. With the exception of firstborn women, we find no evidence of interaction effects of a sibling’s third birth.

Contribution: The study contributes to the literature by testing long-standing hypotheses of fertility contagion for the first time in a plausibly causal design. With the exception of first born women, we find no evidence of contagion effects.

Author’s Affiliation

• Rannveig Hart - Statistisk sentralbyrå (Statistics Norway), Norway EMAIL
• Sara Cools - Institutt for samfunnsforskning (Institute for Social Research), Norway EMAIL

Most recent similar articles in Demographic Research

Harmonised fertility histories in four British longitudinal cohort studies
Volume 54 - Article 18    | Keywords: cohort studies, fertility, harmonised data, United Kingdom

A flexible model for reconstructing education-specific fertility rates: The case of sub-Saharan Africa
Volume 54 - Article 12    | Keywords: Bayesian demography, Demographic and Health Surveys (DHS), education, fertility, fertility rates, sub-Saharan Africa

Learning and reproductive health: Do early cognitive skills contribute to better sexual and reproductive health outcomes among adolescents in Ethiopia?
Volume 54 - Article 7    | Keywords: adolescence, education, education, Ethiopia, fertility, sub-Saharan Africa

Reassessing the U-shaped relationship between gender equality and fertility: A replication and extension of Kolk’s (2019) study using comprehensive gender equality measures
Volume 53 - Article 29    | Keywords: fertility, gender, gender equality, human development, Human Fertility Database (HFD)

Early unintended childbearing and unsecured debt in the United States
Volume 53 - Article 27    | Keywords: demography, fertility, gender, life course, mothers