Combining forward and backward mortality estimation

Demographers often form estimates by combining information from two data sources—a challenging problem when one or both data sources are incomplete. A classic example entails the construction of death probabilities, which requires death counts for the subpopulations under study and corresponding base population estimates. Approaches typically entail ‘back projection', as in Wrigley and Schofield's seminal analysis of historical English data, or ‘inverse’ or ‘forward projection’ as used by Lee in his important reanalysis of that work, both published in the 1980s. Our paper shows how forward and backward approaches can be optimally combined, using a generalized method of moments (GMM) framework. We apply the method to the estimation of death probabilities for relatively small subpopulations within the United States (men born 1930–39 by state of birth by birth cohort by race), combining data from vital statistics records and census samples.     

Estimation of contemporaneous mortality factors

Summary We present methods for solving and making statistical inferences about marginal attack rates based on observed death rates for contemporaneous mortality factors. The general method of solution involves solving a system of nonlinear equations which depend in part on competition coefficients that express the outcome when more than one agent attacks the same host individual. For two factors, we present a detailed analysis of the effect of varying this competition coefficient. Statistical inferences are illustrated using standard large sample approximations (the delta method) and the bootstrap, which is a resampling technique. We also extend the results to allow inferences fork-values.     

Estimation of average mortality under censoring and truncation

In demography mortality is usually reported through averages over time intervals. If average mortality is estimated from censored or truncated data, then direct methods of estimation may create biases that depend on the censoring or truncation distribution. Such discretization errors may be avoided by estimating survival curves first in continuous time, and then discretizing the estimators. We illustrate the different methods on data of the form obtained from family reconstitution.     

Estimation of mortality from orphanhood in adulthood

This paper extends earlier research into methods for estimating adult mortality from information on the recent incidence of orphanhood. It presents a series of regression coefficients for estimating female and male mortality from synthetic cohort data on the subsequent orphanhood of those who had a living mother or father at exact age 20. Such information can be obtained either where questions about parental survival have been asked in two inquiries or by asking retrospectively about dates of orphanhood in a single survey. Although the method is somewhat sensitive to errors in the reporting of ages and dates, it is a promising source of up-to-date estimates of adult mortality that are free from bias due to the underreporting of the orphanhood of young children ("the adoption effect").     

An international comparison of excessive adult mortality

Abstract Empirical expressions derived by Coale and Demeny accurately characterized the relationships among death rates of different age groups for each sex during an extended period of time in Western nations. However, the relationships have changed in recent years, as the mortality of older persons has increasingly exceeded the level expected on the basis of these expressions. The recent disruption is relatively small for females and may be due to very rapid declines in maternal mortality. Among males, the change has been quite pronounced, and it is suggested that increases in cigarette consumption are largely responsible.     

Estimation of local demographic variation in a flexible framework for population projections

A cohort component projection of local populations based on sex and single year of age offers great value for planning local services, but demands data beyond the detail available. Local fertility, mortality and migration schedules by age and sex must be estimated sensitively to local variation if the results are to be of greater value than simpler methods of projection. Two approaches are compared, using data for the recent past: (a) direct estimation of local area age-specific schedules of fertility, mortality and migration based on data available to the national statistical agency; (b) graduation of national schedules using only local area population estimates by age, total numbers of births, and total numbers of deaths; age-specific migration is indirectly estimated from successive population estimates. These two approaches are compared with a projection using the same rates for each area. The three projections have been implemented for electoral wards in the Fife local government area of Scotland, using the flexible framework provided by POPGROUP software. Persuasive local population projections based on standard data for standard areas are feasible without the regular publication of migration flows.     

A census-based method for estimating adult mortality

Abstract A simple method is presented for converting an age distribution in any closed population into the stationary population corresponding to its current mortality conditions. The conversion only requires a set of age-specific growth rates, which will normally be available from successive censuses. From the stationary population, any life table mortality measure of interest can be computed. The index most robust to normal data errors in developing countries is life expectancy, and the paper focuses on its calculation. The sensitivity of results to various forms of data error is considered, and procedures are proposed for removing errors resulting from differential census coverage completeness and from age misstatement at older ages. Applications of the procedures are made to data from Sweden, India and South Korea. Because of the absence of a radix, estimation of life expectancy usually will begin at the fifth birthday.     

Religious involvement and U.S. adult mortality

We use recently released, nationally representative data from the National Health Interview Survey-Multiple Cause of Death linked file to model the association of religious attendance and sociodemographic, health, and behavioral correlates with overall and cause-specific mortality. Religious attendance is associated with U.S. adult mortality in a graded fashion: People who never attend exhibit 1.87 times the risk of death in the follow-up period compared with people who attend more than once a week. This translates into a seven-year difference in life expectancy at age 20 between those who never attend and those who attend more than once a week. Health selectivity is responsible for a portion of the religious attendance effect: People who do not attend church or religious services are also more likely to be unhealthy and, consequently, to die. However, religious attendance also works through increased social ties and behavioral factors to decrease the risks of death. And although the magnitude of the association between religious attendance and mortality varies by cause of death, the direction of the association is consistent across causes.     

Long-range trends in adult mortality: Models and projection methods

In the study reported here, I had two objectives: (1) to test a new version of the logistic model for the pattern of change over time in age-specific adult mortality rates and (2) to develop a new method for projecting future trends in adult mortality. A test of the goodness of fit of the logistic model for the force of mortality indicated that its slope parameter is nearly constant over time. This finding suggests a variant of the model that is called the shifting logistic model. A new projection method, based on the shifting mortality model, is proposed and compared with the widely used Lee-Carter procedure.     

Estimating adult mortality levels from information on widowhood

Summary A range of indirect techniques has been developed for mortality estimation in societies lacking adequate vital registration records. Information on orphanhood has been widely used as an estimator of adult mortality, with generally plausible results. Doubts have remained, however, about potential biases, and the method is less satisfactory for the estimation of male mortality. Information on widowhood, or more strictly the survival of first spouse, has several possible advantages over information on orphanhood. Model first marriage functions and model life tables are used to calculate proportions widowed of first spouse, for both females and males, by marital duration and by age. These proportions widowed are then related to life table survivorship probabilities to provide weighting factors for the conversion of observed proportions widowed into estimates of survivorship probabilities. The application of the method is illustrated with data collected by the 1974 post-enumeration survey of Bangladesh, with apparently encouraging results.     

Education of adult children and mortality of their elderly parents in Taiwan

In societies in which families are highly integrated, the education of family members may be linked to survival. Such may be the case in Taiwan, where there are large gaps in levels of education across generations and high levels of resource transfers between family members. This study employs 14 years of longitudinal data from Taiwan to examine the combined effects of the education of older adults and their adult children on the mortality outcomes of older adults. We use nested Gompertz hazard models to evaluate the importance of the education of an older adult and his or her highest-educated child after controlling for socioeconomic, demographic, and health characteristics at baseline. To gain further insight, we fit additional models based on the sample stratified by whether older adults report serious diseases at baseline. The results indicate that the educational levels of both older adults and children are associated with older adult mortality, but children's education appears more important when we examine the mortality of only those older adults who already report a serious disease. This finding suggests that there may be different roles for education in the onset versus the progression of a health problem that may lead to death.     

Paradox lost: Explaining the hispanic adult mortality advantage

We tested three competing hypotheses regarding the adult "Hispanic mortality paradox": data artifact, migration, and cultural or social buffering effects. On the basis of a series of parametric hazard models estimated on nine years of mortality follow-up data, our results suggest that the "Hispanic" mortality advantage is a feature found only among foreign-born Mexicans and foreign-born Hispanics other than Cubans or Puerto Ricans. Our analysis suggests that the foreign-born Mexican advantage can be attributed to return migration, or the "salmon-bias" effect. However, we were unable to account for the mortality advantage observed among other foreign-born Hispanics.     

Effects of early-life conditions on adult mortality: a review

"This paper considers the effects of health conditions in childhood on an individual's mortality risks as an adult. It examines epidemiologic evidence on some of the major mechanisms expected to create a linkage between childhood and adult mortality and reviews demographic and epidemiologic studies for evidence of the hypothesized linkages....Many empirical studies support the notion that childhood conditions play a major role in adult mortality, but only in the case of respiratory tuberculosis has the demographic importance of a specific mechanism been established by cohort studies. One's date and place of birth also appear to be persistently associated with risks of adult death in a wide variety of circumstances. An individual's height, perhaps the single best indicator of nutritional and disease environment in childhood, has recently been linked to adult mortality, especially from cardiovascular diseases. Further research is needed, however, before causal mechanisms can be identified."     

Predicting adult health and mortality from adolescent facial characteristics in yearbook photographs

Several important longitudinal studies in the social sciences have omitted biomarkers that are routinely recorded today, including height and weight. To account for this shortcoming in the Wisconsin Longitudinal Study (WLS), an 11-point scale was developed to code high school senior class yearbook photographs of WLS participants for relative body mass (RBM). Our analyses show that although imperfect, the RBM scale is reliable (α = .91) and meets several criteria of validity as a measure of body mass. Measured at ages 17–18, the standardized relative body mass index (SRBMI) was moderately correlated (r = .31) with body mass index (BMI) at ages 53–54 and with maximum BMI reported between ages 16 and 30 (r = .48). Overweight adolescents (≥ 90th percentile of SRBMI) were about three times more likely than healthy-weight adolescents (10th–80th percentile of SRBMI) to be obese in adulthood and, as a likely consequence, significantly more likely to report health problems such as chest pain and diabetes. Overweight adolescents also suffered a twofold risk of premature death from all nonaccidental causes as well as a fourfold risk of heart disease mortality. The RBM scale has removed a serious obstacle to obesity research and lifelong analyses of health in the WLS. We suggest that other longitudinal studies may also be able to obtain photos of participants at younger ages and thus gain a prospectively useful substitute for direct measures of body mass.     

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.     

Measurement of adult mortality in less developed countries: a comparative review

"This paper compares the direct and indirect methods used to measure adult mortality in the developing world. No other approach can substitute fully for accurate and complete vital registration, but in many countries it is unrealistic to expect the registration system to cover the majority of the population in the foreseeable future.... The difficulties involved in measuring adult mortality using surveys and other ad hoc inquiries are discussed.... While the choice of methods must depend on each country's situation, direct questions require very large samples and are unreliable in single-round inquiries. On the other hand, although indirect methods provide less detailed and up-to-date information than is ideal, they are adequate for many practical purposes. In particular, the experience of the 1980s suggests that questions about orphanhood perform better than earlier assessments indicated, and recent methodological developments have circumvented some of the limitations of the indirect approach."     

Marriage behavior response to prime-age adult mortality: evidence from malawi

This article examines the effect of AIDS-related mortality of the prime-age adult population on marriage behavior among women in Malawi. A rise in prime-age adult mortality increases risks associated with the search for a marriage partner in the marriage market. A possible behavioral change in the marriage market in response to an increase in prime-age adult mortality is to marry earlier to avoid exposure to HIV/AIDS risks. We test this hypothesis by using micro data from Malawi, where prime-age adult mortality has drastically increased. In the analysis, we estimate the probability of prime-age adult mortality that sample women have observed during their adolescent period by utilizing retrospective information on deaths of their siblings. Empirical analysis shows that excess prime-age adult mortality in the local marriage market lowers the marriage age for females and shortens the interval between the first sex and first marriage.