2.1 Population About the data
Definitions
Data sources
About the data
Knowing the size of a countrys population, its growth rate, and its age
distribution is important for evaluating the welfare of its citizens, assessing the
productive capacity of its economy, and estimating the quantity of goods and services that
will be needed to meet future needs. Thus governments, businesses, and anyone interested
in analyzing economic performance must have accurate population estimates.
Population estimates are usually based on national censuses, but the frequency and
quality of these censuses vary by country. Most countries conduct a complete enumeration
no more than once a decade. Precensus and postcensus estimates are interpolations or
extrapolations based on demographic models. Errors and undercounting occur even in
high-income countries; in developing countries such errors may be substantial because of
limits on transportation, communication, and resources required to conduct a full census.
Moreover, the 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.
Of the 148 economies listed in the table, 129 conducted a census between 1987 and 1997.
The currentness of a census, along with the availability of complementary data from
surveys or registration systems, is one of many objective ways to judge the quality of
demographic data. In some European countries registration systems offer complete
information on population in the absence of a census. See Primary data documentation for
the most recent census or survey year and for registration completeness.
Current population estimates for developing countries that lack recent census-based
population data, and precensus and postcensus estimates for countries with census data,
are provided by national statistical offices or by the United Nations Population Division.
The estimation methods require fertility, mortality, and net migration data, which are
often collected from sample surveys, some of which may be small or have limited coverage.
These estimates are the product of demographic modeling and so are also susceptible to
biases and errors due to shortcomings of the model, as well as the data.
The quality and reliability of official demographic data are also affected by public
trust in the government, the governments commitment to full and accurate
enumeration, the confidentiality of and protection against misuse accorded to census data,
and the independence of census agencies from undue political influence.
Population projections are made using the cohort component method. This method compiles
separate projections of future fertility, mortality, and net migration levels by age and
gender, then applies them to the 1995 base year age and gender structure. Future
fertility, mortality, and net migration levels are determined from demographic models that
use current levels and trends as inputs. Countries where fertility has been falling are
assumed to have further declines at the rate of the previous 10 years until fertility
reaches the replacement level of about two children. In countries where fertility has
remained high, the transition to smaller families is assumed to occur at the average rate
of decline of countries that are currently making this transition. Countries where
fertility is below two children per woman are assumed to remain at this level for another
decade, after which fertility rates will gradually return to replacement level. Similarly,
mortality changes are modeled by assuming that the rate of change in the previous decade
will continue in the near future. Future mortality in countries with high levels of HIV
infection is adjusted to reflect the lagged impact of the disease on mortality.
Definitions
Total population of an economy includes all residents regardless of
legal status or citizenshipexcept for refugees not permanently settled in the
country of asylum, who are generally considered part of the population of their country of
origin. The indicators shown are midyear estimates for 1980 and 1996 and projections for
2010. Average annual population growth rate is the exponential change
for the period indicated. See Statistical methods for more information. Age
dependency ratio is the ratio of dependentspeople younger than 15 and older than
65to the working-age populationthose age 1564. Population
age 60 and above is the percentage of the total population that is 60 or older.
Women age 60 and above is the ratio of women to men in that age group.
Data sources
The World Banks population estimates are produced by the Human Development
Network and the Development Data Group in consultation with the Banks operational
staff. Important inputs to the World Banks demographic work come from the following
sources: census reports and other statistical publications and electronic bulletins from
country statistical offices; demographic and health surveys conducted by national sources;
United Nations Department of Economic and Social Information and Policy Analysis,
Statistics Division, Population and Vital Statistics Report (quarterly), and
Population Division, World Population Prospects: The 1996 Edition; Eurostat, Demographic
Statistics (various years); Council of Europe, Recent Demographic Developments in
Europe and North America 1996; South Pacific Commission, Pacific Island Populations
Data Sheet 1997; Centro Latinoamericano de Demografia, Boletin Demografico (various
years); Economic and Social Commission for Western Asia, Demographic and Related
Socio-Economic Data Sheets 1995; and U.S. Bureau of the Census, World Population
Profile 1996. Projections are based on the methods discussed in Bos and others, World
Population Projections 199495.
THE WORLD BANK METHODOLOGY:
----- On External Debt
Definitions
Debt
indicators
----- On WORLD DEVELOPMENT INDICATORS
Size of the economy
Quality of life
Development progress
Trends in long-term development
Long-term structural change
Key indicators for other economies
Population
Land use and deforestation
Growth of output
Credit, investment and expenditures
Integration with the global economy
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