Multivariate analysis of parity progression—based measures of the total fertility rate and its components

This article describes a methodology for applying a discrete-time survival model—the complementary log-log model—to estimate effects of socioeconomic variables on (1) the total fertility rate and its components and (2) trends in the total fertility rate and its components. For the methodology to be applicable, the total fertility rate (TFR) must be calculated from parity progression ratios (PPRs). The components of the TFR are PPRs, the total marital fertility rate (TMFR), and the TFR itself as measures of the quantum of fertility, and mean and median ages at first marriage and mean and median closed birth intervals by birth order as measures of the tempo or timing of fertility. The focus is on effects of predictor variables on these measures rather than on coefficients, which are often difficult to interpret in the complex models that are considered. The methodology is applicable to both period and cohort data. It is illustrated by application to data from the 1993, 1998, and 2003 Demographic and Health Surveys (DHS) in the Philippines.     

Reconstruction of Birth Histories from Census and Household Survey Data

In this paper a new procedure for reconstructing birth histories from census or household survey data is developed. Given the number of children ever born, the number of deceased children, and the ‘own children’ birth history of each woman, it is possible to ‘fill in’ probabilistically the missing births of her deceased children and of children not present in the household. Thus, the procedure generates complete birth histories from which such measures as age-specific fertility rates, parity progression ratios, and birth interval measures may be estimated. For purposes of illustration and validation, the method is applied to the household survey data of the 1974 Korean National Fertility Survey, both to the entire sample of households, and to households with women from whom individual birth histories were collected. Age-specific fertility rates and parity progression measures estimated from the reconstructed birth histories are compared with those estimated by applying the ‘own children’ method, for the period 1960–74.     

An evaluation of the recent fertility changes in Afghanistan: a parity-specific analysis

Very limited studies exist on the demography of Afghanistan. Using the only national survey with complete birth history data, the 2010 Afghanistan Mortality Survey, this paper describes the recent fertility changes in the country from a parity-specific perspective. From 1995 to 2009, parity progression ratios, average birth intervals, sex ratio at birth by parity and synthetic lifetime average parity are successively examined. Results show that the progression to higher-order births started to decline in the early 2000s and was accompanied by childbearing postponement. The consistency of the parity analysis is assessed by looking at the sex ratio at birth by parity and comparing the synthetic lifetime average parity to fertility estimates computed from other datasets and/or estimation methods. While the sex ratio at birth indicates strong distortion, casting doubt on the ultimate fertility level, the consistency of the parity-based fertility estimates with other fertility estimates corroborates the fact that misreporting the sex of the child is mainly causing the imbalanced sex ratio at birth and is not significantly affecting the level of fertility. The SPPRs-based analysis provides solid evidence that Afghanistan is in the early stage of its fertility transition.     

Period Parity Progression Ratios and Birth Intervals in England and Wales, 1941–1971: A Synthetic Life Table Analysis

A method is presented for analysing maternity history data to provide period estimates of parity progression ratios, birth intervals and related indices. This is applied to a sample of the marriage and maternity histories from the Census of England and Wales of 1971 and shows: (a) a general increase through the 1950s and into the 1960s in period estimates of marriage and parity progression ratios, especially in the progression from first to second birth; (b) a general acceleration of fertility with, again, the second birth interval becoming particularly short and compact; and (c) very steep declines in third and fourth birth progression ratios from the mid-1960s. Birth interval distributions altered during the period examined. Decomposition of a progression-based total fertility index shows change in the ratios for lower birth orders to have dominated the fertility upswing and declines in ratios for higher birth orders to have initiated the subsequent decline.     

Period Parity Progression Measures of Fertility in China

Parity progression measures are uniquely suited to the study of fertility in China, because Chinese policies and programmes focus so closely on parity and birth order. In this paper we present period parity progression ratios for China and its urban and rural areas for the years 1955–81, using the birth history data from the one-per-thousand fertility survey of 1982. Our period parity progression ratios differ from those introduced by Henry in that they provide an overall level of fertility which may be compared with measures based on age-specific birth rates. We compare the two measures empirically for China, finding both similarities and divergences, and then analyse the relation between them. It is suggested that, where fertility is low and fluctuating, as in China, the parity-progression-based measures provide a substantially truer picture of fertility levels and trends than do age-based measures.     

Age at last birth and its components

This paper examines the ways in which the behavior of twentieth century cohorts of American women changed simultaneously in the three components of fertility that determine age at last birth--age at first birth, spacing between subsequent births, and parity progression ratios of subsequent births--to produce changes in the timing of the completion of childbearing. It decomposes changes in the mean age at last birth among cohorts and between whites and nonwhites to changes in these three components. To perform these analyses, we developed and applied a method to estimate the distributions and means of ages and last births, birth intervals, and parity progression ratios from age- and parity-specific fertility rates available from vital statistics data. Results show that the cohorts increased and decreased their age at first birth, birth intervals, and parity progression ratios of lower and higher birth orders in almost every possible combination so as to achieve a relatively young age at final birth.     

Using Discrete-Time Event History Fertility Models to Simulate Total Fertility Rates and Other Fertility Measures

Event history models, also known as hazard models, are commonly used in analyses of fertility. One drawback of event history models is that the conditional probabilities (hazards) estimated by event history models do not readily translate into summary measures, particularly for models of repeatable events, like childbirth. In this paper, we describe how to translate the results of discrete-time event history models of all births into well-known summary fertility measures: simulated age- and parity-specific fertility rates, parity progression ratios, and the total fertility rate. The method incorporates all birth intervals, but permits the hazard functions to vary across parities. It can also simulate values for groups defined by both fixed and time-varying covariates, such as marital or employment life histories. We demonstrate the method using an example from the National Survey of Family Growth and provide an accompanying data file and Stata program.     

Family allowances and fertility: Socioeconomic differences

This article explores socioeconomic differences in the effect of family allowances on fertility. Although several studies have examined the relationship between cash benefits and fertility, few studies have addressed the possible differential effects of cash benefits on families of different income or education levels. I reconstructed the birth histories of women in the past two Israeli censuses of 1983 and 1995 to study socioeconomic differences in the effect of family allowances up to the seventh parity. The results indicate that family allowances have a significant effect at every parity. Using female education as an indicator of socioeconomic status, I find that socioeconomic status is a significant modifier of the effect of family allowances. Family allowances seem to have a relatively large impact on more-educated women.     

A Gompertz model for birth interval analysis

During recent years birth intervals have been analysed on a life table basis. This method retains both closed and open intervals, and so reflects behaviour that deliberately avoids the next birth entirely. When life tables are prepared separately for each birth order, markedly different patterns of movement toward the next birth can appear from one parity to the next. This is illustrated for Korean survey data, with historical trends given across marriage cohorts.

A Gompertz model is found to fit the family of curves that show the cumulative proportion giving birth within each interval closely. Its three parameters have direct intuitive interpretations, one being equal to the parity progression ratio and the other two controlling the pace of childbearing before and after the point of peak activity within the interval. The model is useful for interpolation and projection, and provides an efficient summary of the otherwise cumbersome detail given in a life table. Testing against additional data sets is suggested.     

Cohort estimates of nonmarital fertility for U.S. Women

Historical trends in U.S. nonmarital fertility have been compiled almost exclusively from vital statistics on births. This paper complements this historical record by providing cohort estimates of nonmarital fertility for cohorts of U.S. women spanning approximately 50 years of cohort experience. Life table estimates using retrospective marital and fertility histories in the June 1980, 1985, 1990, and 1995 Current Population Surveys reveal nonnegligible levels of nonmarital fertility historically. For women born between 1925 and 1929, nearly 1 in 10 had at least one nonmarital birth by age 30. For women born between 1965 and 1969, more than 1 of 4 had one or more nonmarital births by age 30, with roughly 1 of5 white, 3 of 5 black, and 1 in 3 Hispanic women having at least one nonmarital birth by age 30. Life table estimates reveal a twofold increase between ages 20 and 30 in the percentage of women with at least one child outside of formal marriage for all cohorts of white and Hispanic women, and an increase of roughly two-thirds for all cohorts of black women. I also document qualitative differences in nonmarital fertility by race/ethnicity, with the percentage of nonmarital births following a divorce or marital separation for white women approximately twice that for black or Hispanic women. Finally, I introduce a new measure, the cohort nonmarital fertility ratio (CNMFR), which provides a cohort complement to the standard period nonmarital fertility ratio. Conservative estimates reveal a roughly threefold increase in the CNMFR for women born from 1925-1929 to 1950-1954 for both whites and blacks, despite substantially higher levels of nonmarital fertility among black women. Overall, these findings reveal surprisingly high levels of nonmarital fertility for women born since the 1920s and confirm that nonmarital fertility has become an increasingly substantial component of overall U.S. fertility.     

中国人口增长之探讨

利用1990年人口普查数据,在1989年生育表基础上,分别以不同的方式改变妇女产次别平均生育年龄和产次别生育率水平这两个变量,仿真推算其变化与平均世代间隔、总和生育率、净再生产率、真实人口增长率及总和递进生育率等指标间的关系,并对中国人口未来发展趋势和政策做了深入的分析探讨。     

Estimating birth stopping and spacing behavior

A decomposition of age-specific marital fertility rates into indices related to spacing and stopping is developed by using Coale and Trussell's indices and the first few parity progression ratios. This approach leads to estimates of the mean birth interval among low-parity births that can be used to address the issue of fertility control early in marriage. In this way the model addresses several of the most serious limitations of Coale and Trussell's approach. The usefulness of the proposed indices is demonstrated by applications to historical data from the United States and Europe.     

Measuring change and continuity in parity distributions

Procedures are developed to allocate the change in mean fertility to the change in specific parities or groups of parities. One procedure uses the proportion at each parity and another uses parity progression ratios. Both are based on the delta method for approximating change in a function of several variables. Drawing on an analogy to survival in a life table, the relational logit model is applied to parity progression. This method allows several parity distributions to be synthesized and to have differences summarized with two parameters. The three procedures are applied to successive cohorts of white U.S. women who completed their childbearing between 1920 and 1980.     

Mortality in Ghana: Evidence from the cape coast project data

Abstract This paper deals with the estimation of mortality for a rural community of about 20,000 persons in the rain-forest area of south-west Ghana. Specifically, infant, child and adult mortality estimates have been obtained by the application of a wide range of direct and indirect methods of measuring mortality from the different statistics collected by a longitudinal mortality and fertility project conducted during 1974-7. It was noted that infant and childhood mortality rates obtained from death registrations were consistent with those rates yielded by pregnancy histories and child survival statistics. However, the adult mortality estimates derived from orphanhood statistics tended to be lower than those suggested by death registrations. The analysis revealed an infant mortality rate of 100 for boys and 84 for girls, equal childhood mortality rates for boys and girls (85-6), a lower expectation of life at birth for men (45.8 years) than for women (52.8), and a much more severe incidence of mortality among men aged over 40 than for women at the corresponding ages.     

Mortality in Ghana: Evidence from the cape coast project data

This paper deals with the estimation of mortality for a rural community of about 20,000 persons in the rain-forest area of south-west Ghana. Specifically, infant, child and adult mortality estimates have been obtained by the application of a wide range of direct and indirect methods of measuring mortality from the different statistics collected by a longitudinal mortality and fertility project conducted during 1974–7. It was noted that infant and childhood mortality rates obtained from death registrations were consistent with those rates yielded by pregnancy histories and child survival statistics. However, the adult mortality estimates derived from orphanhood statistics tended to be lower than those suggested by death registrations. The analysis revealed an infant mortality rate of 100 for boys and 84 for girls, equal childhood mortality rates for boys and girls (85–6), a lower expectation of life at birth for men (45.8 years) than for women (52.8), and a much more severe incidence of mortality among men aged over 40 than for women at the corresponding ages.     

Findings and implications of a correlation analysis of the closed and the open birth intervals

A correlation analysis of data on four fertility variables viz. closed birth interval, open birth interval, age and parity, collected in a survey of about 2,000 married women in the reproductive ages in rural India, is carried out in order to study the interrelationships among these variables. Two hypotheses are formulated governing the relationship of the closed and open birth intervals with the fecundability distribution of fertile women, and Parity Progression Ratios which are largely influenced by the proportion of women becoming sterile after each parity. The data lend support to the hypothesis that while the closed intervals are influenced mainly by the distribution of fecundability of women of non-zero fecundability, the open birth intervals are influenced mainly by Parity Progression Ratios or the proportion of women becoming secondarily sterile after each parity. The analysis suggests that we can use the mean open intervals of women classified by parity as indices of fertility, and such an index is comparable to the index of average age of women of given parity. In areas where it is difficult to ascertain the correct age of women this might be of practical value.     

Do Siblings’ Fertility Decisions Influence Each Other?

Individuals’ fertility decisions are shaped not only by their own characteristics and life course paths but also by social interaction with others. However, in practice, it is difficult to disentangle the role of social interaction from other factors, such as individual and family background variables. We measure social interaction through the cross-sibling influences on fertility. Continuous-time hazard models are estimated separately for women’s first and second births. In addition to individual socioeconomic variables, demographic variables, and an unobserved factor specific to each sibling pair, siblings’ birth events and their timing enter as time-varying covariates. We use data from longitudinal population-wide Norwegian administrative registers. The data cover more than 110,000 sibling pairs and include the siblings’ fertility, education, income, and marital histories. Our results indicate that cross-sibling influences are relatively strong for the respondents’ first births but weak for the second parity transition.     

Changes in the Quantum of Russian Fertility During the 1980s and Early 1990s

To investigate whether Russia's dramatic fertility changes pre‐ and post‐Soviet times were due primarily to tempo effects, as has been argued recently, or to quantum effects, this study standardizes for factors that distort conventional fertility indexes. A time series spanning 1978–93 of period parity‐progression ratios for the Russian Federation is constructed applying the PADTFR technique, which takes into account age, parity, and time elapsed since the birth of the previous child, to data from the Russian micro census of February 1994 (2.8 million maternity histories). Both the fertility rise of the 1980s and the fertility fall of the early 1990s are found to be primarily due to changes in the probability of a second birth. The impact of tempo on the conventional TFR is significant, but of relatively minor magnitude in comparison to changes in the quantum of fertility. The social and economic context in which the fertility change took place is described.     

Ethnic variations in the relationship between income and fertility

The effects of husband'spotential andrelative incomes on completed fertility, as well as their effects on certain parity progression probabilities, are examined within samples of Anglos, Blacks and Mexican Americans. Relationships are estimated using data from the one-percent 1960 and 1970 U.S. Public Use Samples. The results reveal different patterns of relationship by ethnicity between the measures of income and the measures of fertility. The effects on completed fertility of the income measures are positive for Anglos and negative for Blacks, while in the case of Mexican Americans the effect ofpotential income is negative and that ofrelative income is positive. Income effects on the parity progression probabilities are similar in pattern to those from the analyses using completed fertility, although somewhat different patterns tend to appear at different birth orders, especially among Anglos.     

Estimation Of The Birth Rate For The Congo Through Nonconventional Techniques

This paper attempts to produce a set of alternative estimates of birth rates for the Congo and for its main regions through nonconventional techniques. The main body of data used for this purpose is supplied by the demographic survey undertaken during 1955-57. Two types of information on fertility are produced by this survey: (1) births to women by age during the 12 months preceding the survey and (2) children-ever-born to women by age. The available data, while reliable in certain respects, are deficient in others. Thus, the reports on children born during the year preceding the survey are acceptably accurate for the children who have survived but are insufficient for the children who have died.The task was to make the best possible use of various reliable pieces of information directly or indirectly related to fertility, in order to produce some reasonably acceptable estimate of birth rate. One procedure consisted of correcting the reported birth rate for the omission of infant deaths; another procedure involved the adjustment of the reported birth rate with reference to the mean parity of women. In addition to these, an estimate of birth rate was derived by means of stable population technique from the proportion of children under 5 years of age.Three sets of estimates of birth rate, then, have been produced. They yielded a high agreement for the country as a whole, as well as for the provincial and district levels. These estimates were then compared with the proportion of childless women and the proportion of children-the latter having been derived from the records of "continuous registration of inhabitants," a source of information which is completely independent of the demographic survey of 1955-57. Again, a reasonable agreement has been found among all these estimates.Statistical evidence examined in this paper supports a birth rate of about 45 per 1,000 for the Congo. The analysis reveals a high regional variation in birth rate: from 20 per 1,000 (Bas Uele) to 60 per 1,000 (Kivu). This variation is consistent with the variation in sterility level as evidenced by the proportion of women never having had a live birth. The proportion of childlessness varies from 5 percent (Kivu) to about 40 percent (Bas Uele) for women past child-bearing age.