Appendix A - Definitions, Sources, and Methods

Population estimates are usually based on national population censuses, but the frequency and quality of these vary by country. Most countries conduct a complete enumeration no more than once a decade. Pre- and post-census estimates are interpolations or extrapolations based on demographic models.

The dependency ratio (charts 4.4 and 5.3) is the ratio of dependents (persons under age 15 or above age 64) to the working-age population (persons ages 15 to 64). The dependency ratio is an overall measure of the dependence that children and the elderly have on people of working age. However, dependency ratios show the age composition of a population, not necessarily economic dependency. Some children and elderly people are part of the labor force and some working-age people are not.

The world population distribution (chart 5.1) shows each country’s share of the total world population. Total population of an economy includes all residents regardless of legal status or citizenship—except for refugees not permanently settled in the country of asylum, who are generally considered part of the population of their country of origin. The total population presents one overall measure of the potential impact of the country on the world and within its region.

The age composition of the population (chart 5.2) refers to the percentage of the total population that is in specific age groups. Three age groups are presented in chart 5.2: persons under age 15, persons ages 15 to 64 (often referred to as the working-age population), and persons above age 64.

Data for chart 4.4 are from OECD. Data shown in charts 5.1 to 5.3 are from the World Bank.

International comparability of population indicators is limited by differences in the concepts, definitions, data collection procedures, and estimation methods used by national statistical agencies and other organizations that collect population data. Furthermore, ages are not always reported accurately, particularly in developing countries.

Source: OECD, Labor Force Statistics: 1984-2004, 2005 Ed., Paris, August 2005, part I; World Bank, World Development Indicators, Washington, D.C., 2005, table 2.1; and World Bank, World Development Indicators Database, http://www.worldbank.org/.