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Definitions and Sources

  • Gini Index

    Definition: The Gini index measures the extent to which the distribution of income (or in some cases consumption expenditure) among individuals or households within an economy deviates from a perfectly equal distribution. A Gini index score of zero implies perfect equality while a score of one implies perfect inequality.

    Source: Development Data Group, The World Bank. 2006. World Development Indicators 2006 online. Available at http://publications.worldbank.org/ecommerce/catalog/product?item_id=631625. Washington, D.C.: The World Bank.

  • Population living on less than $1/day

    Definition: Population living below $1/day is the percent of the population of a country living on less than $1.08 a day at 1993 international prices (equivalent to $1 in 1985 prices, adjusted for purchasing power parity).

    Source: Development Data Group, The World Bank. 2006. World Development Indicators 2006 online. Available at http://publications.worldbank.org/ecommerce/catalog/product?item_id=631625. Washington, D.C.: The World Bank.

  • Population living on less than $2/day

    Definition: Population living below $2/day is the percent of the population of a country living on less than $2.15 a day at 1993 international prices (equivalent to $2 in 1985 prices, adjusted for purchasing power parity).

    Source: Development Data Group, The World Bank. 2006. World Development Indicators 2006 online. Available at http://publications.worldbank.org/ecommerce/catalog/product?item_id=631625. Washington, D.C.: The World Bank.

  • Poverty Gap at $1/day

    Definition: Poverty Gap $1/day is the mean shortfall from the poverty line (counting the non-poor as having zero shortfall), expressed as a percentage of the poverty line. The shortfall is calculated by averaging incomes (with anything above the poverty line counting as $1) and subtracting that average from the poverty line. This measure reflects the depth of poverty as well as its incidence. The poverty line, in this case, is $1.08 a day at 1993 international prices (equivalent to $1 in 1985 prices, adjusted for purchasing power parity).

    Source: Development Data Group, The World Bank. 2006. World Development Indicators 2006 online. Available at http://publications.worldbank.org/ecommerce/catalog/product?item_id=631625. Washington, D.C.: The World Bank.

  • Poverty Gap at $2/day

    Definition: Poverty Gap $2/day is the mean shortfall from the poverty line (counting the non-poor as having zero shortfall), expressed as a percentage of the poverty line. The shortfall is calculated by averaging incomes (with anything above the poverty line counting as $2) and subtracting that average from the poverty line. This measure reflects the depth of poverty as well as its incidence. The poverty line, in this case, is $2.15 a day at 1993 international prices (equivalent to $2 in 1985 prices, adjusted for purchasing power parity).

    Source: Development Data Group, The World Bank. 2006. World Development Indicators 2006 online. Available at http://publications.worldbank.org/ecommerce/catalog/product?item_id=631625. Washington, D.C.: The World Bank.

  • Access to improved sanitation

    Definiton: Improved sanitation includes any of the following excreta disposal facilities: connection to a public sewer, connection to a septic tank, pour-flush latrine, simple pit latrine, ventilated improved pit latrine, pit latrine with slab, and composting toilet. Improved sanitation facilities are more likely to be sanitary than unimproved facilities, but are not a direct measure of 'basic' sanitation--access to a sanitary system cannot be adequately measured on a global scale.

    Source: World Health Organization (WHO) and United Nation's Children's Fund (UNICEF). 2006. Meeting the MDG Drinking Water and Sanitation Target: The Urban and Rural Challenge of the Decade. Available at http://www.wssinfo.org/pdf/JMP_06.pdf. Geneva: WHO and New York: UNICEF. Data were originally collected under the WHO-UNICEF Joint Monitoring Program.

  • Access to an improved water source

    Definiton: An improved water source includes any of the following types of drinking water sources: household connections, public standpipes, boreholes, protected dug wells, protected springs, and rainwater collection. Improved water sources are more likely to provide safe drinking water than unimproved sources, but are not a direct measure of 'safe' drinking water--access to a safe water supply cannot be adequately measured on a global scale.

    Source: World Health Organization (WHO) and United Nation's Children's Fund (UNICEF). 2006. Meeting the MDG Drinking Water and Sanitation Target: The Urban and Rural Challenge of the Decade. Available at http://www.wssinfo.org/pdf/JMP_06.pdf. Geneva: WHO and New York: UNICEF. Data were originally collected under the WHO-UNICEF Joint Monitoring Program.

  • Literacy rate, all adults

    Definiton: Though it varies across countries, the adult literacy rate is usually defined as the percentage of the population aged 15 years and over who can both read and write, with comprehension, a short, simple statement regarding their everyday life. Literacy data can be used to assess gender, age-group, and geographic patterns of illiteracy within each country, as well as the achievement of national literacy programs and policies. According to UNESCO, "these estimates reflect the performance of the national education system, as well as the quality of the human resources within a country in relation to their potential for growth, contribution to development, and quality of life." Adult literacy correlates with GNP per capita, life expectancy, fertility rates, infant mortality, and urbanization.

    Source: United Nations Educational Scientific, and Cultural Organization (UNESCO) Institute for Statistics. 2006. World Education Indicators, Literacy Statistics. Available online at http://www.uis.unesco.org/ev.php?URL_ID=2867&URL_DO=DO_TOPIC&URL_SECTION=201. Paris: UNESCO.

  • Life expectancy, both sexes

    Definiton: Life expectancy at birth is the average number of years that a newborn baby is expected to live if the age-specific mortality rates effective at the year of birth apply throughout his or her lifetime. The projections reported here assume medium fertility (the 'medium-fertility assumption' of the United Nations Population Division).

    Source: Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat. 2005. World Population Prospects: The 2004 Revision. Dataset on CD-ROM. Available at http://www.un.org/esa/population/ordering.htm/. New York: United Nations.