Volume 12 - Article 5 | Pages 105–106  

Quadratic spline fits by nonlinear least squares

By Carl Schmertmann

Abstract

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.

Software
http://www.demographic-research.org/Volumes/Vol12/5/qsfit/qsfit.html

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

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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