Volume 9 - Article 5 | Pages 81–110  

A system of model fertility schedules with graphically intuitive parameters

By Carl Schmertmann

Abstract

I propose and examine a new family of models for age-specific fertility schedules, in which three index ages determine the schedule's shape. The new system is based on constrained quadratic splines. It has easily interpretable parameters, is flexible enough to fit a variety of "noiseless" schedules well, and is inflexible enough to avoid implausible estimates from noisy data. Across a set of over two hundred contemporary ASFR schedules, the new model fits a majority better, and in some cases much better, than the Coale-Trussell model.
When fit to a recent Swedish time series, model parameters exhibit simple, regular changes over time, suggesting utility in forecasting applications. In simulated small-sample data the new model produces plausible ASFR estimates, with errors similar to Coale-Trussell.

Author’s Affiliation

• Carl Schmertmann - Florida State University, United States of America EMAIL

Other articles by the same author/authors in Demographic Research

Data errors in mortality estimation: Formal demographic analysis of under-registration, under-enumeration, and age misreporting
Volume 51 - Article 9

D-splines: Estimating rate schedules using high-dimensional splines with empirical demographic penalties
Volume 44 - Article 45

Revivorship and life lost to mortality
Volume 42 - Article 17

Editorial: The past, present, and future of Demographic Research
Volume 41 - Article 41

Stationary populations with below-replacement fertility
Volume 26 - Article 14

Quadratic spline fits by nonlinear least squares
Volume 12 - Article 5

Estimating Parametric Fertility Models with Open Birth Interval Data
Volume 1 - Article 5

Similar articles in Demographic Research

Does the women’s employment–fertility U-shape emerge at the local level? Evidence from Italian municipalities
Volume 55 - Article 27    | Keywords: female employment, fertility, gender-equilibrium framework, Italy, local demography, local demography, low fertility

Educational pairings, partners’ economic resources, and second births in Austria
Volume 55 - Article 26    | Keywords: Austria, couples, cure model, fertility, hypogamy, second birth

Projection of family life courses of the descendants of immigrants in England and Wales using microsimulation
Volume 55 - Article 24    | Keywords: England, family, fertility, fertility, microsimulation, migrants, migrants, partnership, population projection, second generation, third generation, United Kingdom, Wales

A personal perspective on the history of the World Fertility Survey and The Demographic and Health Surveys Program: An interview with Tom Pullum
Volume 55 - Article 6    | Keywords: Demographic Health Surveys, fertility, fertility, health, mortality, surveys, World Fertility Survey

Fertility timing and the birth squeeze
Volume 54 - Article 40    | Keywords: birth squeeze, cyclical populations, fertility, marriage, marriage squeeze, stable population