Atechnique for estimating life expectancy with crude vital rates

This paper describes a method of estimating life expectancy at birth on the basis of crude vital rates. The method is derived from stable population theory and it furnishes good estimates insofar as the current crude vital rates of a population are close to its intrinsic rates. This condition is generally met in closed populations which have not experienced sharp movements in fertility. The method is useful for estimating life expectancy in developing nations with good sample registration systems but for which information on age is of poor quality. It is also useful for estimating the movement of life expectancy in certain European nations in the period prior to regular census taking. There are a number of nations and regions in Europe for which long series of birth and death rates are available but for which census age counts are widely spaced.     

Estimation of vital rates for Ghana

Abstract A complete and efficient registration system, of the type which would provide good data on births and deaths, does not exist in Ghana. However, registration of vital events is supposed to be compulsory in 39 towns in the country but the data collected in these areas are too inadequate and defective to provide a sound basis for the analysis of the dynamics of population growth. The results of the censuses conducted by the colonial governments are so defective and unreliable that they do not allow scientific research in the field of population analysis. Before 1960, therefore, when the national census and the post-enumeration survey (based on a 5% sample of the population) were carried out, estimates of fertility and mortality levels were little more than guesses. In this study an attempt has been made to utilize the information on the age-sex composition provided by the 1960 census and post-enumeration survey data on births and deaths to determine, as far as possible, the levels of fertility and mortality and the rates of population growth in Ghana. The fertility estimates-i.e. a crude birth rate of 50, total fertility rate of 6.9 and a gross reproduction rate of 3.4-show that Ghana's fertility is one of the highest in the world. An expectation of life at birth of 40 years, an infant mortality of 160 and a crude death rate of 23 appear to be the most plausible estimates. These estimates yield a rate of natural increase of 2.7% and a growth rate of 3.0% per annum.     

Changing vital rates and age distributions

Abstract In a time of rapid change in birth and death rates demographers need to know the consequences of such changes for age distribution. Does the fall in death rates tend to make the age distribution older? It certainly enables individuals to grow older, but for population aggregates the effect depends on the ages at which mortality improves. Coale, Stolnitz, Schwarz, Lorimer, the United Nations and other writers have investigated trends in age-specific birth and death rates. In particular they have demonstrated that the falling mortality which is now nearly universal does not generally make the population older and sometimes makes it younger. The present article contributes a technique for further examination of this phenomenon.     

Optimal estimate of population age structure with varying vital rates

The author presents a method for estimating the age distribution of a population under varying vital statistics. "Some mathematical aspects of the method, as well as its applicability, will be discussed and numerical simulation will be run to illustrate the results and to compare the method with the traditional estimate of stable population theory...."     

A vital statistics-based procedure for estimating conception rates

A method for estimating conception rates, using vital statistics data, is developed and applied to data on five-year age groups of California women for 1971. The approach is deterministic and allocates total exposure time to the known pregnancy outcomes of live birth, spontaneous abortion, and induced abortion. The population at risk is defined to exclude women who are known to be sterile or sexually inactive. Early fetal loss, premarital conception, and contraceptive use are taken into account. Estimates are made of the fecundability which would obtain ifno contraception were used.     

Estimates of vital rates for the Canadian Indians, 1960–1970

The present paper is an attempt to evaluate the registered data on Canadian Indians collected by the Department of Indian Affairs and Northern Development and to prepare vital rates for 1960–1970 using the adjusted data. A cursory examination of registered data for the purpose of developing various demographic indices and for making future estimates of population indicates certain anomalies that call for a careful appraisal of the data. The main problem is the inconsistency in the reporting of births, due largely to the late registration of births. One plausible reason for late registration may be the increased outward movement of Indians from their reserves. Indirect methods are used to adjust the number of births and infant deaths reported annually since 1960. On the basis of the adjusted data, vital rates for the Canadian Indians are calculated for the period 1960–1970. The crude death rate decreased from 10.9 in 1960 to 7.5 in 1970. The infant mortality rate registered a drastic decline, from 81.5 deaths per 1,000 births in 1960 to 34.9 in 1970. During this same time period the birth rate also declined, from 46.5 to 37.2.     

Estimation of vital rates by means of monte carlo simulation

Monte Carlo simulation has been used to estimate age-specific fertility and mortality rates for a small population,the French-derived isolate of Northside on St. Thomas, U. S. Virgin Islands. Estimates were based on data collected in a household census and genealogical survey and on birth, death, and marriage records for the years 1916to 1966. During this 50-year period (in which the population size increased from 202 to 657), the numbers of births and deaths were too, small to estimate age-specific rates directly, and in addition, death registration was incomplete. Mortality rates were estimated using a simulation program in which mortality was the only stochastic variable. A model mortality schedule was chosen which most accurately reproduced the growth pattern of the population over the 50-year period. To estimate fertility rates, a more complex simulation model was used in which fertility, nuptiality, and mortality were random variables with probability distributions. Preliminary estimates of fertility were made from the birth records and used as input to this simulation program. Birth probabilities were adjusted empirically from one set of simulation runs to the next, until population growth rates, as well as other demographic characteristics, were similar in the real and simulated populations. The birth rates which produced the best fit to the real population data were taken as the estimated age-specific fertility schedule. To reproduce the real population age structure more closely, secular changes in birth probabilities were applied.     

Declining birth rates and growing populations

Excitement over declining fertility in the Third World needs caution for several reasons. First, it is now too late to solve the world's population problem. Second, the common belief that the birth decline is widespread and is affecting virtually all developing nations goes beyond the data. Third, the notion that birth rates are declining with great speed is not true when the rate is measured against either urbanization or mortality decline. Fourth, a sample of countries indicates that the decline is now slowing rather than accelerating. Fifth, the idea that the declines are due mainly to family planning, and can therefore be assured of continuance in the future, seems unwarranted.Revised version of a paper given at the annual meeting of the American Sociological Association, San Francisco, September 7, 1982.     

Population growth rates in perfect contraceptive populations

Eventually, world population must cease to grow. In many countries attempts are made to decrease population growth by providing family planning services to all who want to prevent pregnancies. In this paper we use the concept ‘perfect contraceptive population’,¹ — a population in which no unwanted births occur — to derive estimates of the maximum contribution that prevention of unwanted births might make toward attaining a zero rate of natural increase in population.     

Population growth rates in perfect contraceptive populations

Abstract Eventually, world population must cease to grow. In many countries attempts are made to decrease population growth by providing family planning services to all who want to prevent pregnancies. In this paper we use the concept 'perfect contraceptive population',(1) - a population in which no unwanted births occur - to derive estimates of the maximum contribution that prevention of unwanted births might make toward attaining a zero rate of natural increase in population.     

New estimates of the vital rates of the United States black population during the nineteenth century

The difficulties of obtaining credible estimates of vital rates for the black population throughout the entire nineteenth century are overcome in this study. The methodology employed the notion of deviating networks of mortality rates for each general mortality level, which was taken from the United Nations studyThe Concept of a Stable Population. Period life tables and vital rates for intercensal periods were generated from the new estimates of the black population at each census date. The results of this study are highly compatible both with the life tables for the death-registration states in the twentieth century and the recent Coale and Rives reconstruction for the period from 1880 to 1970 and with several estimates of vital rates previously made for the mid-nineteenth century. This study places the mean life expectancy at birth for the black population during the nineteenth century at about 33.7 years for both sexes. The infant death rate (1000m (0)) is shown to have varied between 222 and 237 for females and between 266 and 278 for males. The intrinsic crude death rate centered on 30.4 per thousand during the century, while the birth rate declined from 53.2 early in the century to about 43.8 at the end.     

Annual fertility rates from census data on own children: Comparisons with vital statistics data for the United States

This paper begins by describing the procedure and data requirements for calculating annual fertility rates from census data on own children. Then, using data from the United States Censuses of 1960 and 1970, fully adjusted estimates are presented and compared with recorded vital statistics rates. Total fertility estimates derived from own children data for whites average less than two percent lower than the recorded rates- a difference that can be attributed partially to the fact that the estimates are adjusted for net census undercount but the recorded rates are not. Even without adjustments for mortality, children not living with their mothers, and net census undercount, the own children data estimates accurately replicate recorded trends (even though the levels are misspecified). The utility of own children data for the study of differential fertility is discussed.     

Methods for gauging the target populations that community colleges serve

For many community colleges, expanding enrollment demands coincide with shrinking resources, confronting policymakers with multiple competing constituencies of discouraged college-goers. At issue are whether community college enrollments are keeping pace with local growth among the subpopulations that typically attend community colleges; how enrollment levels might differ had participation rates remained unchanged; and which specific population groups, in which subareas of an overall region, are most affected by funding constraints. These issues focus attention on identifying and measuring the diverse populations such colleges serve. We present methods for tracking those populations (1) to gauge how completely (or incompletely) the local community college-going population is enrolling in various campuses, and (2) to delineate the functional service areas of individual campuses. Our methods have applicability to the needs of community college systems generally, especially where the size and geographic distribution of their populations are changing significantly through, for example, immigrant influx and regional expansion. These methods and measures add to the applied demographer’s repertoire of techniques for strengthening local decision-making.     

Selection for divergent emigration rates in laboratory populations ofMusca domestica

Summary High and low emigration rates through a laboratory system were selected for in populations of house flies (Musca domestica L.). Emigration consisted of movement of flies from on plastic box to another by way of a connecting tube. Selection was carried out by first dividing a wild population of flies into two lines and then selecting for movement from the box in one line and against movement from the box in the other line. The selection experiment was performed twice. In both experiments a statistically significant difference between the two strains was obtained in three to four generations of selection. In the second experiment, after 5 genrations the mean number of high emigration rate flies emigrating in 1 hour was 4.37 times the mean number of low emigration rate flies and in 24 hours was 2.81 times the number of low emigration rate flies. The second experiment was terminated after 6 generations, but the first experiment was continued for 35 generations. In this case, divergence ceased in roughly 15 generations. The possible relevance of the findings to laboratory population experiments in which spatial discontinuities are included is discussed. This study was supported by a research grant of the National Science Foundation (Environmental Biology GB 4567) to Prof. DavidPimentel. The author wishes to thank Prof.Pimentel for his aid and encouragement.     

Estimating the completeness of reporting of adult deaths in populations that are approximately stable

An elaboration of Preston's (Preston and Hill, 1980) procedure for determining the completeness with which deaths are recorded in approximately stable populations is presented. Both the procedures of Preston and that of Brass are conventionally limited to mortality beyond early childhood, to mortality above age 5 or age 10. The method considered here is based on characteristics of stable populations, i.e., populations that have been subject for a long time to little variation in age-specific mortality schedules or in overall levels of fertility. The essential features of a stable population are maintained even if fertility has changed. This is the case as long as no strong trend in fertility existed more than 15 or 20 years before the date at which the population is observed. Recent changes in fertility may affect the structure of the population at adult ages, but the effect on estimates of completeness of death records can generally be kept within tolerably narrow limits. Prior to showing how explicit estimates of the relative completeness of recording of numbers of deaths and persons can be derived from counts of deaths and persons by age, it is noted that a life table for a stable population can be constructed directly from the recorded distribution of deaths by age, or from the recorded distribution of persons. The procedures described are applied to several different populations in order to illustrate the computational steps necessary to estimate the completeness of death records at ages above childhood in populations that are approximately stable.     

Ties that bind: A case study of the link between employers, families, and health benefits

Most US residents receive health benefits from their employer. Groups of employees and their families are therefore the basis for health care financing. Health care costs rose dramatically during the 1980s and employers looked for ways to control them. One approach is to control the size of the group provided health benefits by an employer. This paper uses a demographic perspective to explore the determinants of change in an employer's group. It examines the linkages among employer policies, employee turnover, and family dynamics. How much control does an employer have over group size? We identify the relative contributions of employment and demographic processes to changing group size. We use a decomposition technique based on matching individual records between consecutive years. We apply this technique to a case study of the health benefits group consisting of General Motors salaried employees and their families. We find that employers face limits to the control that they can exert over the size of the health benefits group associated with their active workforce. Demographic processes unrelated to employee turnover or transfers to layoff or retirement accounted for a large portion of the population change in the case study.     

Mortality rates of elderly Asian American populations based on Medicare and Social Security data

We present sex- and age-specific death probabilities for the elderly of six Asian American subgroups--Chinese, Filipino, Indian, Japanese, Korean, and Vietnamese--based on data from social Security Administration files. We determined ethnicity by combining race, place of birth, surname, and given name. The data source and ethnic determination are the same for deaths and the population at risk, avoiding the problem of noncomparability present when data for the numerator come from vital records and data for the denominator come from census records. We found that death rates for elderly Asian Americans are lower than those for whites, and that socioeconomic differences between subgroups do not translate into like differences in mortality.