| Age-specific fertility rates | The number of births during a year to women in a particular age group, usually per 1,000 women in a 5-year age group at mid-year.2 |
| Age-specific mortality rates | The number of deaths per 1000 persons of a specified age in a particular population.3 |
| Age/sex structure | The composition of a population as determined by the number or proportion of males and females in each age category. The age-sex structure of a population is the cumulative result of past trends in fertility, mortality, and migration.4 |
| Baseline population data | The population, usually by age and sex, for the initial year of a projection.2 |
| Baby boom | 'Baby Boom' is the term applied to the period of time from January 1, 1946 to December 31, 1964 when there was a boom in the birth rate. This period of time saw over 77 million births occur.5 |
| Baby bust | A rapid decline in fertility rates to record low levels during the period immediately after the baby boom.3 |
| Biodiversity | Biodiversity is the term used to describe the existence of a wide variety of species in a particular area or during a specific period of time.5 |
| Carrying capacity | The number of individuals that a habitat or an area can support and sustain with adequate resources is the carrying capacity.5 |
| Cohorts | A group of individuals or couples who experience the same event during a specified period.6 |
| Cohort-component projection method | A method of estimating or projecting a population in which separate components of population change (fertility, mortality, and migration) are used to derive the total population. When such projections are made also by age and sex, the procedure is known as the cohort component method.2 |
| Cohort fertility | Looks at fertility longitudinally, that is at all births occurring to a specific group of women, normally those born or married during a particular year. One is looking over time at their reproductive histories.1 |
| Confidence interval | A confidence interval gives an estimated range of values which is likely to include an unknown population parameter, the estimated range being calculated from a given set of sample data. The width of the confidence interval gives us some idea about how uncertain we are about the unknown parameter. A very wide interval may indicate that more data should be collected before anything very definite can be said about the parameter.7 |
| Demographic factors | Births, deaths, migrations, and other parameters.3 |
| Demographic transition theory | The historical shift of birth and death rates from high to low levels in a population. The decline of mortality usually precedes the decline in fertility, thus resulting in rapid population growth during the transition period.4 |
| Desired fertility | Number of children desired for a family.3 |
| Economic factors | Economic aspects of an activity, country, or person.3 |
| Emigration | The process of leaving one country to take up permanent or semi-permanent residence in another.4 |
| Fertility | Relates the number of live births to the number of women, couples, or very rarely, men.6 |
| Five-year age groups | The age distribution of a population is either given by individual years of age or by age groups, which may be five-year age group, also called quinquennial ages groups, such as 5-9 or 10-14 years. 8 |
| Forecasts | The results of extrapolating a particular past growth of a population into the future when at least some of the independent variables are given in social or economic terms or when the greater or lesser probability of demographic variables is posited in a social-economic framework.3 ALSO, A projection in which the assumptions are considered to yield a realistic picture of the probable future development of a population.8 |
| Households | Socioeconomic units consisting of individuals who live in common dwelling units.3 |
| Immigration | The process of entering one country from another to take up permanent.6 |
| Incidence rates | The number of persons contracting a disease per 1,000 population at risk, for a given period of time.4 |
| Indirect estimation techniques | A body of analytical techniques developed for estimating levels and trends of fertility, mortality, and migration for populations lacking conventional sources of data.3 |
| In-migration | The process of entering one administrative subdivision of a country (such as a province or state) from another subdivision to take up residence.4 |
| Less Developed Countries | Countries that do not have a developed industrial infrastructure.3 |
| Life expectancy at birth | The average number of years a group of people born in the same year can be expected to live if mortality at each age remains constant in the future.2 |
| Life table | Mathematical models in tabular form showing, among other things, the number of persons who have experienced a certain event such as death, first birth, or a divorce by a specified duration, e.g., since birth, since marriage.3 |
| Mean age of childbearing | The mean age of mothers at the birth of their children.1 |
| Migration | Geographic mobility between one locale and another.6 |
| More Developed Countries | Countries that have a developed industrial infrastructure.3 |
| Mortality | Deaths as a component of population change.4 |
| National population censuses | Census: A canvass of a given area, resulting in an enumeration of the entire population and often the compilation of economic information pertaining to that population at a specific time.4 |
| Net migration rates | The difference between the number of migrants entering and those leaving a country in a year, per 1,000 midyear population. May also be expressed in percent. A positive figure is known as a net migration rate and a negative figure as a net emigration rate.2 |
| Number of children ever born | The total number of births a woman has had, regardless of whether the children are living or dead at the time of the inquiry.2 |
| Out-migration | The process of leaving one subdivision of a country to take up residence in another.4 |
| Parity | The number of children previously born alive to a woman; for example, 'two-parity women' are women who have had two children and 'zero-parity women' have had no live births.4 |
| Period measure | Period Analysis: Observation of a population at a specific period of time. Such an analysis in effect takes a 'snapshot' of a population in a relatively short time period -- for example, one year. Most rates are derived from period data and therefore are period rates.4 |
| Population dynamics | Changes in population processes.3 |
| Population momentum | The tendency for population growth to continue beyond the time that replacement-level fertility has been achieved because of the relatively high concentration of people in the childbearing years.4 |
| Population projections | Calculations which show the future development of a population when certain assumptions are made about the future course of population change, usually with respect to fertility, mortality, and migration. They are in general purely formal calculations, developing the implications of the assumptions that are made.8 |
| Prevalence rates | The number of persons having a particular disease at a given point in time per 1,000 population at risk.4 |
| Probabilistic (or stochastic) projections | Projections which consider the probability of various events occurring to individuals over the duration of the process under study. The model may be set out in mathematical formulas or take the form of a simulation where specific values of the variables are included in a system of relations.8 |
| Replacement level fertility | The level of fertility at which a couple has only enough children to replace themselves, or about two children per couple.4 |
| Reproductive years | Women's childbearing years, usually 15-44.3 |
| Stable age structure/ stable population | A population with an unchanging rate of growth and an unchanging age composition as a result of age-specific birth and death rates that have remained constant over a sufficient period of time.4 |
| Stationary population | A stable population in which the rate of natural increase is zero and there is constant size and unchanging age distribution.2 |
| Total fertility rates | The average number of children that would be born alive to a woman (or group of women) during her lifetime if she were to pass through her childbearing years conforming to the age-specific fertility rates of a given year. This rate is sometimes stated as the number of children women are having today. See also gross reproduction rate and net reproduction rate.4 |
| Urbanization | Growth in the proportion of a population living in urban areas.4 |
| Vital rates | Birth rates and death rates.2 |
