Forecasting Fertility: An Application of Time Series Methods To Parameterized Model Schedules

Abstract

This study employs parameterized model schedules of the age profiles of fertility to summarize age-specific rates with a small number of parameters. Time series models of the parameters capture the temporal patterns of the age profiles, and use this information to project the profiles of future vital rates. The model schedules are estimated by application of nonlinear least squares to fertility rates for women aged 14 through 49, for each calendar year from 1917 through 1988. Time series models of the parameters provide a representation of the historical trends of fertility behavior and are employed to forecast fertility profiles. Forecast evaluation over a 10-year holdout sample demonstrates the viability of the methodology. The time series models are updated through 1988 to generate fertility forecasts to the year 2000. The forecasts, showing an increase in the mean age of childbearing and a 9% rise in the total fertility rate, are compared with projections from the U.S. Bureau of the Census.