About the data
Definitions
Data sources
The indicators in this table provide an overview of the quality of life in the 209 economies with populations greater than 30,000 that are included in the World Development Indicators. Except for population density, GNP per capita, and the illiteracy rate, all these indicators appear elsewhere in the book.
Population density is computed from 1995 mid-year population estimates divided by the surface area of the country or economy. Different results may be obtained depending on whether land area or arable land area is used.
Gross national product (GNP) is the broadest measure of national income (see Definitions). GNP per capita in U.S. dollars is used by the World Bank to classify countries for analytical purposes and to determine borrowing eligibility. For definitions of the income groups used in this book, see the Users guide. In calculating GNP in U.S. dollars from GNP reported in national currencies, the World Bank follows its Atlas conversion method. This involves using a three-year average of exchange rates to smooth the effects of transitory exchange rate fluctuations. For further discussion of the Atlas method see Statistical methods.
Relative prices of goods and services not traded on the international market tend to vary substantially from one country to another, leading to big differences in the relative purchasing power of currencies and thus in welfare as measured by GNP per capita. To capture these differences in the relative purchasing power of currencies over equivalent goods and services, table 1.1 also shows GNP per capita estimates that are converted into international dollars using purchasing power parities (PPPs). For an explanation of PPPs see the notes to table 4.14.
Illiteracy rates are problematic statistics. Literacy and illiteracy are difficult both to define and to measure. The definition here is based on the concept of "functional" literacy. To measure literacy using such a definition requires census or sample survey measurements under controlled conditions. In practice, many countries estimate the number of illiterate adults from self-reported data or from estimates of school completion. Because of these problems comparisons across countries—and even over time for one country—should be made with caution.
For additional information on the other indicators see the notes to the tables indicated: population (table 2.1), people living on less than $1 a day (table 2.5), infant mortality rate (table 2.14), total fertility rate (table 2.2), and access to sanitation (table 2.12).
• Population density is the midyear resident population divided by the surface area in square kilometers.
• GNP is the sum of gross value added by all resident producers plus any taxes (less subsidies) that are not included in the valuation of output plus net receipts of primary income (employee compensation and property income) from nonresident sources.
• GNP per capita is the gross national product, converted to U.S. dollars using the World Bank Atlas method, divided by the midyear population.
• GNP per capita in PPP terms is the gross national product converted to international dollars by adjusting for purchasing power parity, divided by the midyear population.
• Poverty is measured as the proportion of the population living on less than $1 a day measured at 1985 prices, adjusted for purchasing power parity.
• Infant mortality rate is the number of deaths of infants under one year of age per 1,000 live births in a given year.
• Total fertility rate is the number of children that would be born to a woman if she were to live to the end of her childbearing years and bear children at each age in accordance with prevailing age-specific fertility rates.
• Adult illiteracy rate is the proportion of adults aged 15 and above who cannot, with understanding, read and write a short, simple statement on their everyday life.
• Access to sanitation refers to the share of the population with at least adequate excreta disposal facilities that can effectively prevent human, animal, and insect contact with excreta. Suitable facilities range from simple but protected pit latrines to flush toilets with sewerage.
The indicators here and throughout the rest of the book have been compiled by World Bank staff from primary and secondary sources. For most of the indicators shown in the tables in this section, the sources are cited in the notes to the tables referred to in About the data. Data on surface area are from the Food and Agriculture Organization (see Data sources for table 3.1). GNP per capita is estimated by World Bank staff based on national accounts data collected by World Bank staff during economic missions or reported by national statistical offices to other international organizations such as the OECD. For high-income OECD economies the data come from the OECD. Data on illiteracy rates are supplied by UNESCO and published in its Statistical Yearbook (see Data sources for table 2.9).