Warren C. Sanderson

The coming acceleration of global population ageing

The future paths of population ageing result from specific combinations of declining fertility and increasing life expectancies in different parts of the world. Here we measure the speed of population ageing by using conventional measures and new ones that take changes in longevity into account for the world as a whole and for 13 major regions. We report on future levels of indicators of ageing and the speed at which they change. We show how these depend on whether changes in life expectancy are taken into account. We also show that the speed of ageing is likely to increase over the coming decades and to decelerate in most regions by mid-century. All our measures indicate a continuous ageing of the world’s population throughout the century. The median age of the world’s population increases from 26.6 years in 2000 to 37.3 years in 2050 and then to 45.6 years in 2100, when it is not adjusted for longevity increase. When increases in life expectancy are taken into account, the adjusted median age rises from 26.6 in 2000 to 31.1 in 2050 and only to 32.9 in 2100, slightly less than what it was in the China region in 2005. There are large differences in the regional patterns of ageing. In North America, the median age adjusted for life expectancy change falls throughout almost the entire century, whereas the conventional median age increases significantly. Our assessment of trends in ageing is based on new probabilistic population forecasts. The probability that growth in the world’s population will end during this century is 88%, somewhat higher than previously assessed. After mid-century, lower rates of population growth are likely to coincide with slower rates of ageing.

The end of world population growth

There has been enormous concern about the consequences of human population growth for the environment and for social and economic development. But this growth is likely to come to an end in the foreseeable future. Improving on earlier methods of probabilistic forecasting, here we show that there is around an 85 per cent chance that the worlds population will stop growing before the end of the century. There is a 60 per cent probability that the worlds population will not exceed 10 billion people before 2100, and around a 15 per cent probability that the worlds population at the end of the century will be lower than it is today. For different regions, the date and size of the peak population will vary considerably.

Are user fees regressive?: The welfare implications of health care financing proposals in Peru

In this paper, we derive a discrete choice model of the demand for medical care from a theoretical model that implies a natural interrelation between price and income. We show that, in the context of a discrete choice model, if health is a normal good, then the price elasticity of the demand for health care must decline as income rises. This implies that the models in previous discrete choice studies which restrict the price effect to be independent of income are misspecified. The model is estimated using data from a 1984 Peruvian survey, and a parsimonious flexible functional form. Unlike previous studies, we find that price plays a significant role in the demand for health care, and that demand becomes more elastic as income falls, implying that user fees would reduce the access to care for the poor proportionally more than for the rich. Our simulations show that user fees can generate substantial revenues, but are accompanied by substantial reductions in aggregate consumer welfare, with the burden of the loss on the poor. These results demonstrate that undiscriminating user fees would be regressive both in terms of access and welfare.

The Demography of Educational Attainment and Economic Growth

Complementing primary education with secondary education in broad segments of the population is likely to give a strong boost to economic growth.

The End of World Population Growth in the 21st Century: New Challenges for Human Capital Formation and Sustainable Development

The 20th century was the century of explosive population growth, resulting in unprecedented impacts; in contrast, the 21st century is likely to see the end of world population growth and become the century of population aging. We are currently at the crossroads of these demographic regimes. This book presents fresh evidence about our demographic future and provides a new framework for understanding the underlying unity in this diversity. It is an invaluable resource for those concerned with the implications of population change in the 21st century.

Average remaining lifetimes can increase as human populations age

Increases in median ages, the most commonly used measure of population ageing, are rapid in todays wealthier countries, and population ageing is widely considered to be a significant challenge to the well-being of citizens there. Conventional measures of age count years since birth; however, as lives lengthen, we need to think of age also in terms of years left until death or in proportion to the expanding lifespan. Here we propose a new measure of ageing: the median age of the population standardized for expected remaining years of life. We show, using historical data and forecasts for Germany, Japan and the United States, that although these populations will be growing older, as measured by their median ages, they will probably experience periods in which they grow younger, as measured by their standardized median ages. Furthermore, we provide forecasts for these countries of the old-age dependency ratio rescaled for increases in life expectancy at birth. These ratios are forecasted to change much less than their unscaled counterparts, and also exhibit periods when the population is effectively growing younger.

Demography. Remeasuring aging.

Adjusting aging forecasts to incorporate increases in longevity and health can provide better tools for policy-makers. Population aging is an international concern, in part because of consequences of coming age-structure changes, e.g., growth in the number of elderly, decline in the number of youth, and accompanying economic and social costs (1–4). These expectations are based on conventional measures of aging that link expected phenotypes to fixed chronological ages. But as life expectancies increase and people remain healthy longer, measures based solely on fixed chronological ages can be misleading. Recently, we published aging forecasts for all countries based on new measures that account for changes in longevity (5–8). Here, we add new forecasts based on disability status. Both types of forecasts exhibit a slower pace of aging compared with the conventional ones.

Expert-based probabilistic population projections

Most users of population projections are interested in one likely path of future population trends based on the best existing knowledge. Whether it is called the medium variant, central scenario, or median of an uncertainty distribution, this projected path will be taken as a forecast on which further considerations can be based. For many users such a best guess will suffice. It can be taken as an exogenous input into their own models for school planning, social security considerations, energy outlook, and the like. For this reason a medium projection is an indispensable component of any set of published projections intended for practical use.

Is the Demographic Dividend an Education Dividend

The effect of changes in age structure on economic growth has been widely studied in the demography and population economics literature. The beneficial effect of changes in age structure after a decrease in fertility has become known as the “demographic dividend.” In this article, we reassess the empirical evidence on the associations among economic growth, changes in age structure, labor force participation, and educational attainment. Using a global panel of countries, we find that after the effect of human capital dynamics is controlled for, no evidence exists that changes in age structure affect labor productivity. Our results imply that improvements in educational attainment are the key to explaining productivity and income growth and that a substantial portion of the demographic dividend is an education dividend.

A behavioral model of the adoption of protective activities

Abstract Considerable empirical evidence suggests that individuals are unwilling to protect themselves against low probability-high loss events even if the costs of protection are subsidized. This behavior has been difficult to rationalize using the traditional expected utility model. This paper proposes a model of adoption of protective activities which emphasizes the importance of interpersonal communication and past experience. The time path of adoption and an equilibrium rate is characterized. Properties of the model shed light on the reasons for low usage of seat belts and limited purchase of federally subsidized flood insurance.