A new technique to estimate infant mortality with an application for El Salvador and Colombia

The paper presents new estimates of infant mortality for Colombia and El Salvador for the years 1950--1970. These estimates are obtained by using a technique which improves on Brass's method in that it suppresses the assumption of constant mortality and introduces instead assumptions about linear and nonlinear changes in mortality risks affecting various cohorts of individuals.     

Migration bias in indirect estimates of regional childhood mortality levels

Demographers often use Brass‐style indirect methods to obtain childhood mortality estimates for regions within developing countries. Regional populations are not closed to migration, however, and mortality reports of women resident in a certain region on the survey date may contain information on events and exposure that occurred elsewhere as the mother migrated. Including this “imported”; mortality information may cause significant bias in regional estimates. In this paper the authors: (1) investigate the possible magnitude of migration bias using a multiregional simulation model, (2) propose a modification to standard methods which should reduce bias in many circumstances, and (3) apply the modified technique to data from Brazil's 1980 Census. We find that migration bias can indeed be significant, and that in the specific case of São Paulo state, imported mortality information may result in overestimates of local mortality levels of 10–15% when using Brass‐style methods.     

Regional trends in fertility and mortality in Brazil

Abstract Questions asked in the 1970 Brazilian census allow the application of fertility and childhood mortality techniques developed by W. Brass. Using some propositions based on fertility estimates from the 1970 census data it was possible to extend the analysis to the 1940, 1950 and 1960 censuses. Estimates are also provided for ten Brazilian regions, for 1940, 1950 and 1970. These estimates show a slight decrease in the fertility level for the country as a whole, but two different trends at regional levels. Between 1940-50 and 1960-70 the poorer regions experienced constant or increasing fertility levels while developed regions experienced declining ones, with only one exception. The mortality estimates indicate a consistent decline in the mortality level of all regions, but also a divergent trend between poor and developed regions, in life expectancies at birth. This work is a summarized version of Chapters II, III and IV of my Ph.D. thesis written under the supervision of Professor D. V. Glass and Mr J. Hobcraft at the University of London. I am most grateful to my supervisors as well as to Professor W. Brass for valuable comments on several aspects of the thesis. While carrying out this study, the author was supported by grants from the Federal University of Minas Gerais, Brazil, and the Ford Foundation.     

Fertility and mortality estimation from the Panama Retrospective Demographic Survey, 1976

Summary Data from the Retrospective Demographic Survey of Panama offer a unique opportunity to test a wide range of methods for estimating indirectly basic demographic parameters from inaccurate and incomplete data. Our primary emphasis is to evaluate methods for estimating adult mortality from information on widowhood and orphanhood, though estimates of childhood mortality obtained from information on sibling and child survivorship are assessed as well. The results for most of the estimating procedures are consistent; this finding is encouraging because it lends support to the hypothesis that the techniques can provide good estimates of mortality. Methods which produce results which are inconsistent provide valuable lessons. In particular, methods for providing unconditional estimates of values ofl (x) for adults by combining directly information on childhood mortality and adult mortality are shown to produce estimates which predominantly reflect the level of childhood mortality employed. Furthermore, within-method consistency of estimates appears to be a very poor indicator of reliable performance of the estimating technique or quality of data, since most methods yielded estimates which were internally consistent, though estimates made by different methods could differ considerably. In summary, the analysis indicates a birth rate of around 35 per thousand, a death rate of around 7.5 per thousand, a total fertility ratio of about 4.8, and expectations of life at birth of approximately 59 and 64 years for men and women respectively.     

Maternal union instability and childhood mortality risk in the Global South, 2010–14

Efforts to improve child survival in lower-income countries typically focus on fundamental factors such as economic resources and infrastructure provision, even though research from post-industrial countries confirms that family instability has important health consequences. We tested the association between maternal union instability and children’s mortality risk in Africa, Latin America and the Caribbean, and Asia using children’s actual experience of mortality (discrete-time probit hazard models) as well as their experience of untreated morbidity (probit regression). Children of divorced/separated mothers experience compromised survival chances, but children of mothers who have never been in a union generally do not. Among children of partnered women, those whose mothers have experienced prior union transitions have a higher mortality risk. Targeting children of mothers who have experienced union instability—regardless of current union status—may augment ongoing efforts to reduce childhood mortality, especially in Africa and Latin America where union transitions are common.     

New midyear age-sex-color-specific estimates of the U.S. population for the 1940s and 1950s: including a revision of coverage estimates for the 1940 and 1950 censuses

This paper describes new midyear (July 1) estimates of the "true" population of the United States by age, sex, and color (white, nonwhite) for the 1940s and 1950s. It also presents the corresponding implied coverage estimates for the 1940 and 1950 censuses. The new population estimates are calculated by combining the most recent figures on the 1960 population with estimates of the demographic components of change for the 1950s and 1940s in an iterative reverse cohort-component projection algorithm. Among the principal findings of the new estimates are: (a) existing midyear estimates of the "true" population in the 1950s are 450,000 to 500,000 too high; (b) existing age-specific estimates for the 1950s tend to underestimate the population at the older ages (55 years and over) and overestimate the population in the young and middle adult years (15 to 54 years); (c) estimates of the "true" population in the 1940s were too low except for nonwhites at ages 65 and over; (d) existing estimates of percentage net undercount and underenumeration for the 1950 and 1940 censuses tend to be too high, substantially so for nonwhites in the 1940 Census; and (e) nonwhites were more completely enumerated in 1940 than in 1950. Thus, in addition to being methodologically and temporally consistent with post-1960 estimates, the new population estimates described here imply some substantial revisions in demographic, social, and economic statistics for the two decades prior to 1960.     

Infant mortality in the Marshall Islands

Levy and Booth present previously unpublished infant mortality rates for the Marshall Islands. They use an indirect method to estimate infant mortality from the 1973 and 1980 censuses, then apply indirect and direct methods of estimation to data from the Marshall Islands Women's Health Survey of 1985. Comparing the results with estimates of infant mortality obtained from vital registration data enables them to estimate the extent of underregistration of infant deaths. The authors conclude that 1973 census appears to be the most valid information source. Direct estimates from the Women's Health Survey data suggest that infant mortality has increased since 1970-1974, whereas the indirect estimates indicate a decreasing trend in infant mortality rates, converging with the direct estimates in more recent years. In view of increased efforts to improve maternal and child health in the mid-1970s, the decreasing trend is plausible. It is impossible to estimate accurately infant mortality in the Marshall Islands during 1980-1984 from the available data. Estimates based on registration data for 1975-1979 are at least 40% too low. The authors speculate that the estimate of 33 deaths per 1000 live births obtained from registration data for 1984 is 40-50% too low. In round figures, a value of 60 deaths per 1000 may be taken as the final estimate for 1980-1984.     

The measurement of historical trends in fetal mortality in England and Wales

This paper critically discusses recent attempts to estimate long-term trends in the stillbirth rate for England and Wales. It assesses the available historical evidence for the level of late-fetal mortality, drawing especially on examples from Norway, Sweden, and Denmark. A theoretical fetal-infant life table for a high-mortality population is also outlined as a means of analysing the relationship between segments of the conception-to-first-birthday mortality curve. Finally, new estimates of the stillbirth rate for England and Wales are proposed, based on variations in the early neonatal and maternal mortality rates during the 1930s. These estimates are substantially lower than the earlier estimates and are more in keeping with the available evidence from northern Europe. The implications of the revised estimates for interpretations of historical changes in mortality patterns are also considered.     

Estimation of adult mortality using forward and backward projections

Summary In this paper it is shown that, contrary to our intuitive understanding of the nature of population projection, the estimation of adult intercensal mortality leads to different results depending on whether forward or backward projection of the population is used. From this result a simple procedure is developed that yields estimates of the completeness of adult mortality registration. Finally, the nature and performance of a variety of methods that have recently been developed to estimate adult mortality in the absence of accurate data are compared.     

The measurement of historical trends in fetal mortality in England and Wales

This paper critically discusses recent attempts to estimate long-term trends in the stillbirth rate for England and Wales. It assesses the available historical evidence for the level of late-fetal mortality, drawing especially on examples from Norway, Sweden, and Denmark. A theoretical fetal–infant life table for a high-mortality population is also outlined as a means of analysing the relationship between segments of the conception-to-first-birthday mortality curve. Finally, new estimates of the stillbirth rate for England and Wales are proposed, based on variations in the early neonatal and maternal mortality rates during the 1930s. These estimates are substantially lower than the earlier estimates and are more in keeping with the available evidence from northern Europe. The implications of the revised estimates for interpretations of historical changes in mortality patterns are also considered.     

Retrospective evidence of a decline of fertility and child mortality in Bangladesh

A detailed analysis of survey data collected in 1961–1962 for a sample of 4200 families in central East Pakistan produced consistent and reasonable estimates of birth and death rates for the preceding decade. Extremely high levels of infant and child mortality declined noticeably in the period 1952–1961. Age-specific birth rates to married women also decreased in the decade for women over the age of 19, while a small increase was recorded for married women aged 15 to 19. During the 1950s total marital fertility declined about one-fifth. Birth rates remained high in 1960 according to these estimates, but there is reason to anticipate further reductions in birth rates, particularly among older women. To improve understanding of the determinants of fertility and to aid in the formulation of policy to cope with population trends, statistical analysis must increasingly consider information on families over time. Retrospective household survey data may provide the empirical base for this line of inquiry.     

The estimation of adult mortality in Africa from data on orphanhood

Summary Until recently, very little information has been available about the levels and patterns of adult mortality in tropical Africa, but during the past decade several countries have included questions in censuses and surveys as to whether a person's father and mother are still alive. From the data so obtained, estimates of adult mortality have been prepared. This paper compares the results of three such exercises with alternative estimates of adult mortality derived from other sources. In the case of Chad, the orphanhood data obtained in the demographic sample survey of 1964 yielded estimates of mortality which agreed reasonably closely with those obtained from questions on deaths of household members occurring during the twelve months preceding the survey. The latter data however were themselves subject to substantial errors and had to be corrected using techniques based on stable population theory. For Kenya, the orphanhood questions were included in the 1969 census and the results were compared with the mortality estimates derived from inter-censal survival from 1962 to 1969. Once again, the data obtained from the latter were subject to error but in general appeared to be consistent with the orphanhood estimates. The third comparison was made from Malawi, where alternative mortality figures were available from the Malawi Population Change survey which was a 'dual record' type of operation, conducted in 1971/2. The agreement in this case was remarkably close, once the number of deaths had been corrected for omissions by both systems with allowance for positive correlation. It is concluded that as a simple and inexpensive technique of estimating adult mortality, the orphanhood approach has much to recommend it.     

A flexible two-dimensional mortality model for use in indirect estimation

Mortality estimates for many populations are derived using model life tables, which describe typical age patterns of human mortality. We propose a new system of model life tables as a means of improving the quality and transparency of such estimates. A flexible two-dimensional model was fitted to a collection of life tables from the Human Mortality Database. The model can be used to estimate full life tables given one or two pieces of information: child mortality only, or child and adult mortality. Using life tables from a variety of sources, we have compared the performance of new and old methods. The new model outperforms the Coale-Demeny and UN model life tables. Estimation errors are similar to those produced by the modified Brass logit procedure. The proposed model is better suited to the practical needs of mortality estimation, since both input parameters are continuous yet the second one is optional.     

Estimates of mortality from infant mortality rates

Estimates of mortality rates and expectation of life at birth, using infant mortality rates, are examined on the basis of 150 life tables for both sexes. Least squares linear estimates are given as well as estimates of their variances. Model life table calculations, as proposed by the U.N. Population Branch, are then compared with these unbiased minimum variance estimates and shown to overestimate the expectation of life by more than two years on the average, and to be at most 68% efficient. Though better estimates are provided in this paper, their variance is still so large as to cast doubt on the practical usefulness of anv estimates based exclusively on infant mortality rates.     

Estimating infant and childhood mortality under conditions of changing mortality

Summary It is well known that estimates of infant mortality obtained using Brass's technique are very accurate. Biases are introduced, however, when one or more of the assumptions on which it relies are violated. Departures from the assumption of constant fertility may be handled by using a variant of the technique which depends on information on the age distribution of surviving children, rather than on indexes of the fertility function. Violations of the assumption of constant mortality - an increasingly common situation in most developing societies - produce upward biases in the estimates. The amount of bias is a function of the speed of mortality decline, the characteristics of the fertility pattern and, finally, of the age of the mother. This paper presents a simple technique which corrects these biases, and in addition, generates estimates of the parameters of the mortality trend. It differs from others in that it uses a cohort definition of mortality decline and relies on knowledge of the age structure of surviving children rather than on indexes of the fertility pattern.     

Methods of adjusting the stable estimates of fertility for the effects of mortality decline

Summary The paper shows how stable population methods, based on the age structure and the rate of increase, may be used to estimate the demographic measures of a quasi-stable population. After a discussion of known methods for adjusting the stable estimates to allow for the effects of mortality decline two new methods are presented, the application of which requires less information. The first method does not need any supplementary information, and the second method requires an estimate of the difference between the last two five-year intercensal rates of increase, i.e. five times the annual change of the rate of increase during the last ten years. For these new methods we do not need to know the onset year of mortality decline as in the Coale-Demeny method, or a long series of rates of increase as in Zachariah's method.     

On long-term mortality trends in the United States, 1850–1968

This study of United States life tables analyzes the process of mortality transition during 1850–1968. Special features of the study are (1) a phase-specific, rather than an age-specific, analysis of mortality and (2) use of measures based on person-years of life (nL _x ) in phase-intervals, rather than survival rates (nPx) or expectation of life at given ages (e _x ^o). The analysis suggests that the historical transition of mortality in the United States can be described as a three-stage process: an initial stage of slow improvement in life expectancy during 1850–1900, a second stage of rapid improvement during 1900–1950, and a third stage of slower improvement since 1950. Quantitative measures of rapidity of mortality decline in the several phases indicate that they are not identical for all phases and in all stages. The analysis also suggests that there have been rapid changes in the components of overall mortality differentials by sex and race in the United States. The paper draws attention to the need for studies of factors in variations of mortality at ages beyond 50 in the United States population subgroups.     

Methods for combining ancillary data in stochastic compartment models of cancer mortality: generalization of heterogeneity models

"We present a mortality model where nationally representative survey data on risk factor distributions are combined with data on cohort mortality rates to increase information, i.e., a fixed marginal risk factor distribution is combined with a cohort model representing unobserved individual risk heterogeneity. The model is applied to lung cancer mortality in nine U.S. white male cohorts aged 30 to 70 in 1950 and followed 38 years. Estimates of the cohort specific proportions of smokers were made from the National Health Interview Survey. Comparisons are made for models with different patterns of changes with age of individual heterogeneity." (SUMMARY IN FRE)     

An evaluation of brass mortality estimates under conditions of declining mortality

An evaluation of the Brass childhood mortality estimates under conditions of declining mortality shows them to overestimate current mortality. Error increases as the rate of mortality decline increases, as the childhood age up to which cumulative mortality is being estimated increases, and as age at onset of childbearing decreases. We use the results to develop a method for correcting the Brass estimates for the effects of quasistability. The method requires an estimate of the rate of mortality decline within the population in addition to information on the pattern of childbearing in the population.     

New african American life tables from 1935–1940 to 1985–1990*

New life tables for African Americans are presented from 1935 through 1990. They are based on a historical series of vital statistics data on deaths that have been corrected for age misreporting, on reconstructed population counts that have been adjusted for census underenumeration, and on births that have been corrected for underregistration. The new life tables show rapid mortality declines for both African American males and females from 1935 to 1950, and relatively steady reductions thereafter for females. The smaller declines in male mortality in young adulthood and middle age since the 1950s have led to exceptionally high ratios of male to female mortality at these ages. Corrections for census undercounts lead to higher values of life expectancy than in official life tables, but to less improvement over time. Official estimates of life expectancy at age 65 appear to be about 10% too high around 1940 but only about 1.5% too high in the late 1980s.