Glossary

Census
The total process of collecting, compiling and publishing demographic, economic and social information pertaining to a specific time for all persons in a country or delimited part of a country.
Cohort
A group of people sharing a common demographic experience who are observed through time. For example, an age cohort, is a group of individuals who are the same age that are observed over time.
Cohort component population projection
Projects the population by age groups and by other attributes such as sex and in some cases, ethnicity. The tool is based on the components of demographic change including births, deaths and migration.
Composition of population
Distribution of people by different characteristics including age, sex, marital status, household size, household attributes, educational attainment, occupation, labor force participation and income.
De facto
Population that is physically present
De jure
Usual place of residence
Demography
The study of human population with respect to size, composition, spatial distribution and changes in the population that occur over time.
Density of population
The number of people who occupy a given area or unit of land.
Doubling time
The number of years it takes a locale to double in population size.
Estimation (of population size)
A calculation of the size of a population for a year between census takings or for the current year.
Extrapolation
A projection tool that uses past and current census information to project the future size of a population.
Forecast
Is a projection that includes judgment statements concerning the future. When planners forecast, they alter information in a projection to meet their vision of the future.
Life table
Measures mortality, survivorship and life expectancy for each age group of a population. Age-specific death rates are applied to a hypothetical cohort of newborn babies. The table records the probability of dying, probability of surviving and the life expectancy for each age of this hypothetical cohort of newborn babies.
Population Pyramids
A graphic tool to study the age and sex distribution of a population.
Projection
A calculation of the size of the population for a future date in time.
Prorating
Projection tools that rely on the projection of a larger or parent population to project the population size of a sub-area.
Rate
Measures the frequency of a demographic event occurring in a population.
Ratio
Measures the size of a population group, a in terms of another population group, b such as the sex ratio which measures males in terms of females.
Survival rate
The probability of a given age group surviving into the next age group.
Vital registration system
A method of recording vital events such as births, deaths, fetal deaths, marriages and divorces that occur among a population.

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