The World Population.

Authors Avatar

Population, term referring to the total human inhabitants of a specified area, such as a city, country, or continent, at a given time. Population study as a discipline is known as demography. It is concerned with the size, composition, and distribution of populations; their patterns of change over time through births, deaths, and migration; and the determinants and consequences of such changes. Population studies yield knowledge important for planning, particularly by governments, in fields such as health, education, housing, social security, employment, and environmental preservation. Such studies also provide information needed to formulate government population policies, which seek to modify demographic trends in order to achieve economic and social objectives.

Methods of research

National censuses, civil registration, and, since the 1960s, national sample surveys are the major sources of demographic data. They provide the raw materials for investigating the causes and consequences of population changes. The most common source is the population census, a count of all persons by age and with specified social and economic characteristics within a given area at a particular time. A register is a continuous record of births, deaths, migrations, marriages, and divorces, often maintained by a local government; reliability varies with the scrupulousness of citizens in reporting these data. In the sample survey, a statistically selected portion is used to represent the total population.

In the U.S., decennial censuses have been taken since 1790. Since the 1950s the U.S. Bureau of the Census has conducted an annual Current Population Survey, a highly detailed sample survey of many aspects of demographic behaviour and related socioeconomic factors. International population data are compiled in systematic form by the United Nations Statistical Office, which prepares an annual Demographic Yearbook; by the United Nations Demographic Division, which issues biennial assessments and projections of world population; and by the International Bank for Reconstruction and Development.

Join now!

Measures of population

The numbers of births, deaths, immigrants, and emigrants over a specified time interval determine the change in population size. For comparative purposes, these components of change are expressed as proportions of the total population, to yield the birth rate, death rate, migration rates, and the population growth rate. (Birth and death rates typically are stated as numbers per 1,000 population per year.) These rates are affected by the age-composition of the population; for example, a very healthy population, which, as a result, has a relatively large proportion of old people, might have a death rate similar to ...

This is a preview of the whole essay