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This is an expanded version of comments on the future of the demography of aging at an invited session of the 2008 annual meeting of the Population Association of America. In an introduction, John Haaga offers reasons for a revival of interest in population aging, including greater realization of plasticity in aging trajectories at both individual and societal levels. Linda Martin proposes that population scientists working in aging emulate those studying fertility and family planning in previous decades, learning from interventions (in this case, aimed at increasing retirement savings and reducing disability at older ages). Changes in family structure will increasingly affect new cohorts of the elderly, and Linda Waite speculates on the ways in which changes in the economy, medicine, and the legal environment could affect the social context for aging. Research on mortality at older ages is “alive and well” asserts James Vaupel, who sets out six large questions on mortality trends and differentials over time and across species. Lastly, Wolfgang Lutz expands the scope of projections, showing the considerable uncertainty about the timing and pace of population aging in the developing world and the effects on future elderly of the increases in educational attainment in much of the world during the second half of the twentieth century.

Mortality data for 30 mostly developed countries available in the Kannisto–Thatcher Database on Old-Age Mortality (KTDB) are drawn on to assess the pace of decline in death rates at ages 80 years and above. As of 2004 this database recorded 37 million persons at these ages, including 130,000 centenarians (more than double the number in 1990). For men, the probability of surviving from age 80 to age 90 has risen from 12 percent in 1950 to 26 percent in 2002; for women, the increase has been from 16 percent to 38 percent. In the lowest-mortality country, Japan, life expectancy at age 80 in 2006 is estimated to be 6.5 years for men and 11.3 years for women. For selected countries, average annual percent declines in age-specific death rates over the preceding ten years are calculated for single-year age groups 80 to 99 and the years 1970 to 2004. The results are presented in Lexis maps showing the patterns of change in old-age mortality by cohort and period, and separately for men and women. The trends are not favorable in all countries: for example, old-age mortality in the United States has stagnated since 1980. But countries with exceptionally low mortality, like Japan and France, do not show a deceleration in death rate declines. It is argued that life expectancy at advanced ages may continue to increase at the same pace as in the past.

Studies in fertility in the industrialized world primarily focus on the decline in average fertility and the determinants of this trend (Bongaarts 2002; UN Population Division 2003; Morgan 2003; Caldwell and Schindlmayr 2003). Variation in fertility within a population is used in an instrumental manner to link birth rates to explanatory variables by means of regressions and de compositions. The recent comprehensive work by Frejka and Sard?n (2004) reviewed changes in completed cohort fertility in industrialized countries and related them to changing age and parity patterns. The present study is interested primarily in the inter-individual diversity in fertility according to the parity distributions of women. This way of think ing about the inter-individual diversity is related to the concentration (or Lorenz) curve, showing what proportion of women have what proportion of children. Such a curve would demonstrate, for example, that 30 percent of American women born in 1931-32 have half of the children born to this cohort, while half of these women have 75 percent of the children. At the same time, 62 percent of children born to this cohort were born to mothers with four or more children, while only 3 percent were born to mothers with one child. These quantities describe something that might be called a division of labor in the matter of fertility (Vaupel and Goodwin 1987). The division of labor concept can be expressed also by an average inter-individual difference in childbearing "productivity" among women. It can be shown, for example, that the average difference between any pair of women (including women who remained childless) from the 1931-32 American cohort in the number

THE NUMBER OF oldest old persons in China, defined here as aged 80 and older, is calculated by the United Nations to climb from about 11.5 million in the year 2000 to 27 million in 2020, 39 million in 2030, 64 million in 2040, and 99 million in 2050. 1 Under the UN’s medium fertility assumption, 2 the percent aged 65 and older is expected to increase from 6.9 in 2000 to 15.7 in 2030 and 22.7 in 2050, while the share of the oldest old which in 2000 is 13 percent of the elderly population will be some 30 percent in 2050. The main reason the number of oldest old will climb so quickly after 2030 is that China’s “baby boomers,” who were born in the 1950s and 1960s, will fall into the category of “oldest old” at that time. During 2000‐50 the population of the oldest old will grow faster than any other age group in China. This phenomenon is not limited to China. The average annual rates of increase of oldest old persons between 2000 and 2050 are expected to be around 4.3 percent in China, India, and Mexico and 2.2‐2.8 percent in Canada, Japan, the United States, Germany, and France (UN 2001b). The rate of increase of the Chinese oldest old subpopulation is much faster (4.4 percent vs. 2.7 percent) than that of the entire elderly population aged 65 and older. The oldest old are much more likely to need help in daily living than the younger elderly. The oldest old consume medical care and other services and benefits of government and private transfers far out of proportion to their numbers. As evidenced later in this article, the proportion of individuals leading active daily lives declines and the disability rate increases dramatically with age among the Chinese oldest old. Torrey (1992: 382) estimated that in the United States, the Medicare costs of those aged 80 and older are 77, 60, and 36 percent higher than those of the younger elderly aged 65‐69, 70‐74, and

This paper develops a multidimensional model for projecting households using conventional demographic data. A brief review of the three kinds of major models for family household projection is presented as well as an illustrative example of the application of the proposed model with a sensitivity analysis on how demographic changes can affect households and population dynamics. It is noted that the model and its associated software ProFamy contribute to the development of methods for projecting family structures in several ways. First the model permits projection of many characteristics of households and their members. Second it can closely link the projected household and its members characteristics with future demographic rates. Third it includes nuclear family and three-generation households as well as all individuals in the population at the starting year of projection. It also updates their survival status and other demographic statuses. Moreover the model is useful for scenario analysis of the long-term consequences of alternative policy direction. It also has the potential of performing satisfactorily for shorter- term forecasts.

To IMPROVE POPULATION forecasting in the future, demographers should conduct more thorough assessments of the accuracy of past projections. Research should also focus on making greater use of: (1) models that include marriage, divorce, cohabitation, morbidity, and other demographic events that influence fertility, mortality, and migration as well as models that break populations down by educational achievement, employment status, and other variables; (2) models that take account of economic, social, and environmental dynamics, including integrated structural models and models with constraints; and (3) forecasting approaches that systematically quantify uncertainty. A further area that requires rethinking is the appropriate use of expert judgment in population projections. Finally, new ways need to be developed for distributing software for making population forecasts and for disseminating the results of alternative forecasts.

It is widely assumed that mortality at advanced ages is attributable to old age per se and that death rates at advanced ages cannot be substantially reduced. Using a larger body of data than previously available the authors find that developed countries have made progress in reducing death rates even at the highest ages. Furthermore the pace of this progress has accelerated over the course of the twentieth century. In most developed countries outside Eastern Europe average death rates at ages 80-99 have declined at a rate of 1 to 2 percent per year for females and 0.5 to 1.5 percent per year for males since the 1960s. For an aggregate of nine countries with reliable data through 1991 the annual average rate of improvement between 1982-86 and 1987-91 was 1.7 percent for male octogenarians and 2.5 percent for female octogenarians. (SUMMARY IN FRE AND SPA) (EXCERPT)

For cohorts of U.S. women completing their fertility from 1917 to 1980 roughly a fifth to a quarter of the women had half the children. This concentration of reproduction is analyzed by tracing time series of various summary measures and by plotting concentration curves that display the relationship between proportions of women and proportions of children. Concentration analyses may be relevant to policy decisions especially those relating to the targeting of an intervention. If a fifth of women are bearing half the children perhaps policies to reduce (or to increase) births should be directed toward this group. (SUMMARY IN FRE AND SPA) (EXCERPT)

Data from Chinas 1982 one-in-a-thousand fertility survey are used to construct contour maps (called Lexis maps) of various surfaces of Chinese marriage and fertility. They offer a panoramic view of the interaction of age period and cohort variations. The maps clearly display long-term trends of the past 3 decades: age of 1st marriage has shifted upward by about 4 years and fertility has dramatically declined especially before age 20 and after age 30. The maps also reveal the substantial impact of disruptions associated with the Great Leap Forward the Cultural Revolution and the mobilization of urban school graduates for work in rural and mountaineous areas as well as the increase in marriage and fertility associated with the new Marriage Law announced in 1980. Because the maps display age and time simultaneously the effect of long-term trends and short-term disturbances on the age-composition of marriage and fertility can be seen. Marriage continues to occur largely within a 5-year period of age although this period has shifted from 15-19 to 20-24; childbearing has been drastically concentrated in the ages from 21-28. Amidst the turbulent change 2 striking regularities persist. Marriage although delayed remains virtually universal by age 35 and fertility among married women younger than 26 remains as high as it has been over the last 30-40 years. Between ages 19-26 about 1/3 of married women bear a child a year. One important implication of the patterns over the last 3 decades is that China will be burdened with a jagged age structure perhaps for a century or more.