Volume 12 - Article 5 | Pages 105-106

Quadratic spline fits by nonlinear least squares

By Carl Schmertmann

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Date received:02 Sep 2004
Date published:22 Mar 2005
Word count:0
Keywords:fertility, fertility models, quadratic splines, software
Weblink:Please click here for the software.
 Publication 9-5 is also linked to this.


This web program fits a Quadratic Spline model, as described in Schmertmann (2003; Demographic Research Volume 9, Article 5), to any empirical fertility schedule supplied by the user. The fit minimizes the sum of squared differences between the empirical nfx values and the nfx values from the QS model schedule. Output includes parameter estimates, a graphical depiction of the fitted schedule, and several text reports. Users do not need specialized statistical software or a particular operating system to run the program; the only requirement is a web browser.


Author's Affiliation

Carl Schmertmann - Florida State University, United States of America [Email]

Other articles by the same author/authors in Demographic Research

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

» A system of model fertility schedules with graphically intuitive parameters
Volume 9 - Article 5

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

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