Jacob S. Siegel

Estimates of coverage of the population by sex, race, and age in the 1970 census

Several estimates of total net underenumeration and of net census errors by sex, race (white, Negro-and-other-races, Negro), and age (five-year groups) in the 1960 and 1970 Censuses, for the total population of the United States, derived by the methods of demographic analysis, are presented. The different data, procedures, and assumptions employed in developing the various estimates are described briefly, and the findings are then discussed in terms of a”preferred” set of estimates. The preferred set of estimates of corrected population for 1970 combines estimates for persons under age 35 based directly on birth, death, and migration statistics, estimates for females aged 35 to 64 based on the Coale-Zelnik estimates (white) for 1950 or the Coale-Rives estimates (Negro) for 1960, estimates for males aged 35 to 64 based on the use of expected sex ratios, and estimates for the population 65 and over based on”Medicare” enrollments and expected sex ratios. These estimates indicate an overall net underenumeration of 5.3 million persons or 2.5 percent in 1970, as compared with 5.1 million or 2.7 percent in 1960, and a net underenumeration of 1.9 percent for whites and of 7.7 percent for Negroes in 1970, as compared with 2.0 percent and 8.0 percent, respectively, in 1960. As in 1960, undercoverage in 1970 was greatest for Negro males (9.9 percent); net error rates exceeded 12 percent in each age group 20 to 49 and reached 17 to 19 percent at ages 25 to 44. All sex-race groups showed marked increases between 1960 and 1970 for children under ten and marked declines at ages ten to 24. Equally reliable estimates of population coverage cannot be prepared for states and smaller geographic units or for the population of Spanish ancestry.

On the demography of aging

This paper is concerned with the contributions of demography to gerontology or the demography of aging. The major interests of gerontological demographers and outstanding issues and problems are discussed in terms of the process of aging. Problems of definition of old age and aging are noted in terms of: 1) the lack of a universally acceptable definition of normal biological aging and 2) the variance of cultural definitions of old age. The demographer usually defines old age by age boundaries but recent advances have begun to define old age in terms of longevity e.g. the number of years until death. This concept has certain economic social legal and ethical implications. For instance a chronically ill person could claim the benefits of old-age legislation at a younger age than a healthy person. Demography of aging is grounded in the theory of growth and structure of population. Many studies have shown that in the aging of populations fertility is the determining factor not mortality. Contrary to popular belief the next several decades will see that the past record of births is expected to dominate the changes in the future numbers of elderly. Mortality declines will play a secondary role. Given current trends it is possible that the United States will see unprecedented high levels (17%) of elderly people. One of the most important facts and problems of the older years in industrialized countries is the large excess of women which leads to problems of isolation for many elderly women. Mortality and longevity are important in the demography of aging. Key issues are: 1) the analysis of factors in past declines in fertility rates 2) the possibilities and prospects of extending life expectancy and span 3) the problem of measuring socioeconomic differentials in mortality and 4) the possibilities of reducing group differences. Demographers continue to hold an interest in the differences in the variation between death rates and the variation between the life expectancy values. Demographers study the health status of the elderly the health care delivery system the allocation of resources for health care and the relation between morbidity and mortality. Geographic distribution and mobility of the elderly are also important to demographers. Gerontological demographers are particularly interested in measurement and analysis of the life cycle. They measure age period and cohort factors which affect the life cycle and construct multiple decrement tables which are useful to analyzing labor force participation migration expectancy and family formation and dissolution. One principal area in which demography and geronotology converge is in the study of marital composition and living arrangements of the elderly as well as the family cycle. Societal dependency measurements work experience and retirement prospects are also important areas of study.

DEVELOPMENT AND ACCURACY OF PROJECTIONS OF POPULATION AND HOUSEHOLDS IN THE UNITED STATES

The history of the official U. S. projections of population and house-holds in recent decades is briefly reviewed, with particular attention to methodology and the relation of the methodology to the accuracy of the projections. The introduction of the cohort-component procedure in the 1930’s opened the way for separate analysis of the trend of the components of births, deaths, and net immigration in connection with making population projections. As a further development, the period-fertility method of projecting births gave way in the 1960’s to the cohort-fertility method. Consideration is now being given to various methods involving parity-progression procedures. Some alternative methods and problems of measuring the accuracy of population projections are then considered. The percent “error” in the projected population growth, by components and age, and the range from high to low expressed as a percent should also be examined in addition to the percent “error” in the total population. However accuracy is measured, the projections made in the 1930’s and 1940’s were often wide of the mark, and those made in the 1950’s and 1960’s failed to anticipate the sharp changes which occurred, even though the actual figures usually fell within the range projected. Elaboration of projection methodology has not resulted in any great increase in the precision of the projections, largely because birth rates have fluctuated widely, and the fluctuations have proven difficult, if not impossible, to predict. The projections of households have had a roughly similar history, and the methods and problems of evaluation are somewhat similar. Their development has been characterized by the introduction of alternative and changing “headship” rates and increasing disaggregation of the data and procedures. The paper concludes with some generalizations based on U. S. experience. Although refinement of methods may contribute little to accuracy, accuracy is only one aspect of the usefulness of projections. The need for conditional projections and their analytical usefulness are such that there is no question that we should confidently continue to make them.

Some aspects of the use of birth expectations data from sample surveys for population projections

The value of national sample survey data relating to birth expectations for projecting births is reassessed in the light of data limitations pointed out by Ryder and Westoff among others and of the methods of projection used by the United States Bureau of the Census. The annual level of fertility under the cohort-fertility projection method depends on the assumptions regarding completed fertility, about which the available survey data are fairly informative, and on the assumptions regarding the timing of births, about which the survey data tell us very little. Test calculations suggest that Ryder and Westoff have overstated the significance of timing relative to completed family size for the level of future births. We believe that the fall in the annual total fertility rate in the first half of the sixties is to be explained only in part by a general delay in childbearing; a moderate to substantial decrease in completed family size has also occurred. Analysis of the latest set of fertility projections of the Census Bureau also suggests that the assumptions about completed fertility are a much more important determinant of the level of future births than timing, both in the short and long term. Although the available expectations data cannot help in predicting short-term annual changes in fertility, they appear useful for making long-term projections of annual fertility. Expansion of the size, frequency, and content of the sample surveys and incorporation of parity and birth interval into the projection method may improve projections.

The Methods and Materials of Demography.

Presents an exposition of the methods used by technicians and research workers in dealing with demographic data. This book is concerned with the ways data on population are gathered, classified, and treated to produce tabulations and various summarizing measures that reveal the significant aspects of the composition and dynamics of populations.