The potential economic returns to the demographic transition are high. As countries move from a steady state with high mortality and high fertility to an equilibrium with low mortality and fewer children, lower dependency ratios, higher investment in human and physical capital as well as...

Health is a key component of human development. This article looks at how health is measured, and the convergence of health across countries. We argue that health measures should account for illness as well as mortality, but in practice life expectancy is a reasonable proxy for population...

This paper examines data on urbanization. We review the most commonly used data sources, and highlight the difficulties inherent in defining and measuring the size of urban versus rural populations. We show that differences in the measurement of urban populations across countries and over time...

We add health and longevity to a standard model of life-cycle saving and show that, under plausible assumptions, increases in life expectancy lead to higher savings rates at every age, even when retirement is endogenous. In a stationary population these higher savings rates are offset by...

There are two approaches to reducing the burden of sickness and death associated with the human immunodeficiency virus (HIV), which leads to acquired immunodeficiency syndrome (AIDS): treatment and prevention. Despite large international aid flows for HIV/AIDS, the needs for prevention and...