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A system of model fertility schedules with graphically intuitive parameters

 

Carl Schmertmann

 
VOLUME 9 - ARTICLE 5
 
Date Received: 28 May 2003
Date Published: 10 Oct 2003

http://www.demographic-research.org/volumes/vol9/5/

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The following additional files belong to this article. Click the icon to view the files. To save them click the icon with the right mouse button and choose "Save target as..." or "Save link as..."
file All Files (zip)
file FILE I QS Model
file FILE II CT and QS fits to international schedules
file FILE III CT and QS fits to international schedules
file FILE IV QS fits to Swedish time series

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

Keywords
age-specific fertility, age-specific rates, Coale-Trussell, estimation, fertility, models, splines

Related links
file Please also see the new software with publication 12-5.

Word count (Main text)
5200

Other Articles by the same author/authors (in Demographic Research)
file[12-5] Quadratic spline fits by nonlinear least squares
file[1-5] Estimating Parametric Fertility Models with Open Birth Interval Data

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