Estimating parametric fertility models with open birth interval data.
Explore the source record for details and available documents.
Americas↗
Biomedical subjects
C P Schmertmann
Publications and source records attributed to C P Schmertmann.
Fertility estimation from open birth-interval data.
Censuses and surveys frequently collect information on period fertility through questions on the timing of last births. The standard approach to estimating fertility with open-interval data uses the proportion of women giving birth in the year before the interview. I propose a more efficient, maximum likelihood method for estimating fertility from open-interval data. I illustrate a mathematical derivation of the new method, perform sensitivity analyses, and conduct empirical tests with Brazilian census data. The new estimators have small biases and lower variance than standard estimators for open-interval data. Consequently, the new method is more likely to generate accurate results from small or moderately sized samples.
Adolescent↗
Three strikes and you're out: demographic analysis of mandatory prison sentencing.
Much of the debate about the costs and benefits of "three-strikes" laws for repeat felony offenders is implicitly demographic, relying on unexamined assumptions about prison population dynamics. However, even state-of-the-art analysis has omitted important demographic details. We construct a multistate life-table model of population flows to and from prisons, incorporating age-specific transition rates estimated from administrative data from Florida. We use the multistate life-table model to investigate patterns of prison population growth and aging under many variants of three-strikes laws. Our analysis allows us to quantify these demographic changes and suggests that the aging of prison populations under three-strikes policies will significantly undermine their long-run effectiveness.
Adolescent↗
An introduction to nonparametric regression in demographic research.
"My intent in this...paper is to alert demographers to the existence of useful new methods, known collectively as nonparametric (NP) regressions, that have been made possible by reductions in computing costs over the last several decades. NP regressions use brute force computing power to free researchers from the need to make strong a priori assumptions about functional forms, thus allowing greater flexibility and accuracy in modelling relationships than in standard parametric approaches. Increased flexibility and computing power do not eliminate the central role of theory in guiding social science research, but they free empirical analysis from the requirement that relationships between variables must have mathematically convenient shapes....I begin this paper with a discussion of bias-variance tradeoffs in regression models, followed by a discussion of localized regression. Subsequent sections discuss specific NP techniques for bivariate and multivariate regressions, with examples. Throughout this paper I will illustrate with data from 17,851 mothers aged 15-45 who were interviewed in the 1988 U.S. National Maternal and Infant Health Survey." (SUMMARY IN FRE)
Americas↗
Demographic influences on the number of children at school entry ages, with examples from three states.
"This paper analyzes the effects of changes in fertility, mortality, and net migration patterns on the growth of school entry-age populations in three states (Florida, South Carolina, and West Virginia) over the period 1950-1990. Fertility changes have had the largest influence on growth of these young populations, as common sense suggests. Changing migration patterns have been quite important, however, in explaining intertemporal and interspatial variations in growth rates."
Age Distribution↗
Immigrant's ages and the structure of stationary populations with below-replacement fertility.
A sustained regime of low fertility plus immigration yields an unusual kind of stationary population. The author demonstrates that all stationary populations have a common structure, and that the familiar replacement-level fertility population is the youngest among the many stationary populations corresponding to a particular life table. This finding has important consequences for policy because although fertility increase and immigration are equally effective at halting population decline, immigration is inferior as a means of rejuvenating low-fertility populations. In fact, an immigration-based policy could make a low-fertility population older rather than younger. The paper includes examples using U.S. and West German vital rates.
Adolescent↗