Some results from asian population growth studies

Abstract Coverage estimates of births and deaths derived from the matching experience of a relatively comprehensive group of studies conducted in Asia and employing dual collection systems are resented and analysed. Major conclusions based on these Asian studies include: (1) coverage of live births has generally been more complete than that for deaths; (2) nevertheless, unadjusted rates of natural increase tend to be underestimates; (3) there is great variability within each type of collection system in the coverage rates observed; and (4) one-time household surveys, as a group, seem to be particularly subject to underreporting of vital events.     

Maternal mortality in South Africa: lessons from a case study in the use of deaths reported by households in censuses and surveys

South Africa is unique in being a developing country which has asked questions on pregnancy-related deaths in both its 2001 census and 2007 household survey, and monitors maternal and pregnancy-related mortality through vital registration and a confidential enquiry into maternal deaths. These sources of data provide a wide range of estimates of maternal mortality for the country. This paper examines these estimates to assess to what extent the differences between them are due to data deficiencies, methodological deficiencies or definitional differences. The results show that since maternal deaths are relatively rare it is fairly difficult to establish the maternal mortality rate with a great degree of accuracy in a setting where data are less than perfect. They also show that to some extent the differences are due to differences and errors in processing of data but that pregnancy-related mortality should not be treated as synonymous with maternal mortality. However, after adjustment, pregnancy-related mortality from vital registration was comparable with the level that may be expected using several alternative approaches, while the rate reported by households in census and surveys was about double that from vital registration. Nonetheless, all the data indicate an upward trend in maternal mortality that is in keeping with the impact of the HIV/AIDS epidemic, which is likely to have contributed to the discrepancies.     

Toward a New Conceptualization of Settlements for Demography

It has long been recognized that where people live and work can be a relevant factor in helping to explain demographic behavior, yet the treatment of location in censuses and surveys remains surprisingly crude. Emphasis is still being given to the urban–rural dichotomy based on definitions that most countries around the world introduced 40 to 50 years ago and have modified little since. Given the increase in the complexity of settlement systems in recent decades in less developed as well as in more developed contexts, this simple classification is no longer adequate for examining the role of settlement in demographic processes. The time has come to rethink how settlement should be differentiated in population data collection and analysis. Contemporary technologies and methodologies make it possible to analyze spatially referenced data in ways that are more rapid and sophisticated than could have been imagined when the conventional approach was devised.     

A study of the correlation bias of unrecorded events by two independent enumeration systems

Summary In this paper the allegation that, when using the Chandrasekar-Deming technique with two independent enumeration systems to record the incidence of vital events and migrations, each individual system misses the same type of event is investigated. If this correlation bias were to occur frequently enough, it could result in a serious underestimation of a given type of event. Using vital events and migrations data derived from a longitudinal survey conducted in Liberia between 1969 and 1973, the estimated number of recorded events is tabulated into homogeneous groups that are demonstrated to affect omission rates. The proportion of missed eyents is computed separately for each enumeration system, and the presence or absence of a significant correlation mathematically determined. The results of this study suggest that no significant correlation could be demonstrated in the type of birth, death or infant death that was commonly missed by each individual enumeration system. This indicates that the omission of a birth, death or infant death was apparently a random occurrence as far as the individual casefinding systems were concerned. The authors conclude that any underestimation of vital events from this type of correlation bias may not be as serious as originally imagined. In contrast to this observation, the omission of particular types of migrations by each enumeration system was apparently not a random occurrence, but was associated with the direction of migration. This implies that selected migration rates in the liberian survey were probably understated and this could happen in other longitudinal surveys, unless specific precautions are taken to avoid it.     

A study of the correlation bias of unrecorded events by two independent enumeration systems

In this paper the allegation that, when using the Chandrasekar-Deming technique with two independent enumeration systems to record the incidence of vital events and migrations, each individual system misses the same type of event is investigated. If this correlation bias were to occur frequently enough, it could result in a serious underestimation of a given type of event. Using vital events and migrations data derived from a longitudinal survey conducted in Liberia between 1969 and 1973, the estimated number of recorded events is tabulated into homogeneous groups that are demonstrated to affect omission rates. The proportion of missed eyents is computed separately for each enumeration system, and the presence or absence of a significant correlation mathematically determined. The results of this study suggest that no significant correlation could be demonstrated in the type of birth, death or infant death that was commonly missed by each individual enumeration system. This indicates that the omission of a birth, death or infant death was apparently a random occurrence as far as the individual casefinding systems were concerned. The authors conclude that any underestimation of vital events from this type of correlation bias may not be as serious as originally imagined.

In contrast to this observation, the omission of particular types of migrations by each enumeration system was apparently not a random occurrence, but was associated with the direction of migration. This implies that selected migration rates in the liberian survey were probably understated and this could happen in other longitudinal surveys, unless specific precautions are taken to avoid 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."     

Social Indicators in Surveys of Urban Aboriginal Residents in Saskatoon

The Bridges and Foundations Project on Urban Aboriginal Housing, a Community-University Research Alliance (CURA) project financed primarily by the Social Sciences and Humanities Research Council of Canada (SSHRC) and the Canada Mortgage and Housing Corporation (CMHC), has been operational in Saskatoon since early 2001. During these past 5 years over 50 specific research projects, community surveys, graduate theses, workshops, conferences, seminars and other meetings have been conducted under the auspices of the Bridges and Foundations Project as a whole. This paper first discusses the various social indicators employed in seven surveys, which probed deeply into the views of local Aboriginal residents of their quality of life, particularly their living conditions and affordable housing. The paper focuses less on the vast amount of data gathered from some 2,000 residents than on the relevance of social indicators used in these surveys—for example which were most or least informative, and which were of most or least interest and pertinence to the residents themselves. In the process it would seem pertinent to discern which of various research approaches seemed, in retrospect, to have been most appropriate, informative and beneficial. The paper then proceeds to place our experience in the Bridges and Foundations Project within a broader theoretical discussion of social indicator development; and concludes with a brief commentary on the linkages between theory and research and between academic and community-based research.     

Bayesian population reconstruction of female populations for less developed and more developed countries

We show that Bayesian population reconstruction, a recent method for estimating past populations by age, works for data of widely varying quality. Bayesian reconstruction simultaneously estimates age-specific population counts, fertility rates, mortality rates, and net international migration flows from fragmentary data, while formally accounting for measurement error. As inputs, Bayesian reconstruction uses initial bias-reduced estimates of standard demographic variables. We reconstruct the female populations of three countries: Laos, a country with little vital registration data where population estimation depends largely on surveys; Sri Lanka, a country with some vital registration data; and New Zealand, a country with a highly developed statistical system and good quality vital registration data. In addition, we extend the method to countries without censuses at regular intervals. We also use it to assess the consistency of results between model life tables and available census data, and hence to compare different model life table systems.     

A system of social indicators for the CMEA countries and for Hungary

This paper discusses the reasons for the growing demand for social indicators in Hungary and in other European socialist countries. A brief history of the construction of a system of social indicators within the framework of the Council of Mutual Economic Aid is given. The subsystems and the main indicators are described. The present practice and the problems of social classifications used in the social indicator systems and in social surveys are treated. In addition to the existing data sources of social indicators, sample surveys were considered to be necessary to provide a full and detailed view of Hungarian society. In addition to objective indicators, recently, subjective indicators have also been collected.     

Time Use by Gender and Quality of Life

Italy has no survey that was specifically designed to measure the degree of quality of life for the population, although certain other surveys exist which contribute useful information on the issue. This paper will concentrate on the potential of using existing sample surveys and on initial studies carried out starting from the Time Use survey conducted by the National Statistical Institute in 1989.Daily activities are the key factor when analysing a person's quality of life, however, these must also be considered in context. First and foremost this context is the household, within which each person carries out more or less defined roles. The roles covered are, in fact, a crucial variable when evaluating each person's quality of life. This angle of obsevation is particularly instructive when seen in terms of developments from a gender standpoint. Interpreting a woman's lifestyle according to the presence of symmeetry of asymmetry of roles, accompanying this analysis with one covering subjective perception of satisfaction as to daily activities, is an essential approach for determining the real satisfaction derived from the different aspects of a person's daily life. In addition to conventional indicators, newly conceived indicators taking into account the division of roles can be of great help when carrying out this kind of study. In this sense the analysis of individual time use in relation to household time use represents a significant step forward when studying quality of life.     

The Pattern of Age-Specific fertility rates

A study of the pattern of age-specific fertility rates by five-year age-groups has revealed the possibility of using the Pearsonian type I curve as a graduating equation. Such distinctions have been examined for fifty countries having high, medium, and low fertility rates. Results have been found to be quite satisfactory, even when, for purposes of simplicity, the parameters have been restricted to depend on the first two moments, instead of the first four. The number of independent parameters has thus been reduced to only three, and method shave been suggested for their estimates, using ancillary information which is usually provided in the census reports. The findings seem to be particularly useful for countries lacking effective registration systems of vital events such as births related, as they are, to the age of the mother.In short, the determination of a series of age-specific fertility rates depends primarily on the modal fertile age (a1) and on one of the two exponents (m, or m2) of the type I distribution. It has been shown that the proportions of women married in the age groups 20-24 years and 25-29 years can be used for approximate evaluations of both of these parameters. While estimates of a, and m, are sufficient to generate a relative distribution of age-specific fertility rates, actual values can be obtained if, in addition, the annual number of births is either known or can be estimated from census age distributions of children.Modal distributions of relative values of age-specific fertility rates (such that the sum of these rates adds up to 100.0) have also been obtained for different combinations of al and m1, but are not shown here for lack of space. Once the estimates of al and m, have been made, the modal tables can always be referred to for the corresponding distributions of age-specific fertility rates.     

Sample registration in India

India's ad hoc sample registration scheme for obtaining current estimates of rural birth and death rates for the whole country is being implemented quite rapidly. Five states have 140 sample units, and eleven states will have from 20 to 100 units in the study depending upon the stage of implementation by March, 1967.Essential elements of the project for each unit are: (1) continuous registration of vital events by a paid part-time local enumerator, (2) a six-month household survey to detect births and deaths which occurred during the previous six months, and (3) matching events from registration and surveys and field recheck of unmatched events to obtain the "best" count of real number of events. Preliminary results in a non-random sample indicate that the crude birth and death rates are around 37.1 and 15.7 per 1,000, respectively, for India's rural population, but these probably will be found to be on the low side.Most of the problems of implementation are operational or administrative rather than statistical: (1) For various reasons, some states are slow in agreeing to assume financial and other responsibilities for the scheme. (2) In many states, even after the scheme has been accepted, there are delays in recruiting the staff, training, and so forth. (3) The most serious problem in the whole project is maintaining control of field operations well enough at each stage to insure that prescribed instructions and methodology are being followed.Experience in India indicates that staged implementation of such projects is highly desirable when trained staff are limited. There still are a number of methodological problems which must be tested as the sample registration evolves. Sample registration is one of the first steps in the Indian program to. develop an adequate vital statistics system. Exploratory studies to measure completeness of civil registration are being done now in an effort to develop means of using civil registration data alone for measurement of vital rates.     

Government statistics: The conflict between research and privacy

The production of social statistics has been challenged in certain West European nations by the "privacy issue." Privacy advocates contend that computerized data files containing information about individuals endanger personal privacy and other civil liberties. The privacy issue has taken two forms: anti-census campaigns and data protection systems. Although those responsible for statistical data have traditionally safeguarded their records, they are often drawn into this issue. Increasingly, they have had to deal with the sociopolitical environment through legislative liaisons, lawyers, and advertising agencies. They have also had to revise data collection and processing procedures. In some situations, they have had to suspend censuses and surveys.     

The Level and Age Pattern of Mortality in Bandafassi (Eastern Senegal): Results From a Small-Scale and Intensive Multi-Round Survey

The data collected in the Bandafassi demographic study in Eastern Senegal, a small-scale intensive and experimental follow-up survey of a population of about 7,000 in 1983, were analysed to derive an estimated life table. The use of multi-round surveys, combined with anthropological methods to estimate ages and collect genealogies, has resulted in unusually reliable data. Taking into account the uncertainty of the estimates due to the small size of the population, mortality was high, with life-expectancy at birth close to 31 years; a pattern of infant and child mortality close to that observed in other rural areas of Senegal, with a very high level or mortality between ages six months and three years; a seasonal pattern in child mortality with two high-risk periods, the rainy season and the end of the dry season; an adult mortality pattern similar to that described in model life tables for developed countries; no significant difference by sex or ethnic group. The Bandafassi population study and a few similar studies suggest that one possible way to improve demographic estimates in countries where vital registration systems are defective would be to set up a sample of population laboratories where intensive methods of data collection would continue for extended periods.     

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.     

Reexamining the Dominance of Birth Cohort Effects on Mortality

The association between birth cohort and subsequent mortality has been of interest especially following publication of studies around 1930 of cohorts born up to the latter part of the nineteenth century, particularly for England and Wales. Updated results are presented for this population, together with those for two other cohorts, twentieth‐century Japanese and British populations born about 1930, which have been identified as having particularly clear‐cut birth cohort patterns, and which are used to underpin incorporation of cohort effects in both British official and actuarial mortality forecasts. Graphical methods used to identify cohort patterns are discussed. A number of limitations and difficulties are identified that mean that the conclusions about the predominance of cohort effects are less robust than often assumed. It is argued that alternative explanations should be considered and that the concentration on birth cohorts with particularly advantaged patterns may distort research priorities.     

Migration and Father Absence: Shifting Family Structure in Mexico

Despite many changing demographic processes in Mexico—declining adult mortality, rising divorce, and rising nonmarital fertility—Mexican children’s family structure has been most affected by rising migration rates. Data from five national surveys spanning three decades demonstrate that since 1976, migration has shifted from the least common to the most common form of father household absence. Presently, more than 1 in 5 children experience a father’s migration by age 15; 1 in 11 experiences his departure to the United States. The proportions are significantly higher among those children born in rural communities and those born to less-educated mothers. The findings emphasize the importance of framing migration as a family process with implications for children’s living arrangements and attendant well-being, particularly in resource-constrained countries. The stability of children’s family life in these regions constitutes a substantial but poorly measured cost of worldwide increases in migration.     

A theory of technophysio evolution, with some implications for forecasting population, health care costs, and pension costs

We argue that over the past 300 years human physiology has been undergoing profound environmentally induced changes made possible by numerous advances in technology. These changes, which we call technophysio evolution, increased body size by over 50%, and greatly improved the robustness and capacity of vital organ systems. Because technophysio evolution is still ongoing, it is relevant to forecasts of longevity and morbidity and, therefore, to forecasts of the size of the elderly population and pension and health care costs.     

The contraceptive prevalence survey project: content and status

The United States Agency for International Development (USAID) selected Westinghouse Health Systems to carry out contraceptive surveys. The primary objectives of the Contraceptive Prevalence Surveys (CPS) are to determine periodically the levels of contraceptive use in the country; to examine the correlates of and differentials in these levels in order to assess the impact of various types of governmental and nongovernmental programs; to identify factors that will facilitate an increase in contraceptive use, particularly factors involved in program planning activities; and to institutionalize in each country the capability to design and implement studies of contraceptive prevalence, to be undertaken at regular intervals by an in-country agency. Each CPS generally collects data on the basic demographic background of the country concerned, knowledge of contraceptive methods, prior contraceptive experience and current method used, past fertility behavior and future fertility intentions, present utilization of various types of service delivery systems, perceived accessibility of contraceptives, and reasons for nonacceptance of contraception. In the CPS project, data collection and field operations have been strongly stressed. Efforts have recently been made to expand the extent and sophistication of CPS data analysis. For example, 2 countries are currently using a series of mathematical techniques called synthetic estimators to estimate subnational levels of contraceptive use by merging CPS and census data. Westinghouse, in cooperation with the University of Michigan, is currently working to develop community characteristics module for inclusion in future CPS projects.