The Demopædia Encyclopedia on Population is under heavy modernization and maintenance. Outputs could look bizarre, sorry for the temporary inconvenience

Multilingual Demographic Dictionary, second unified edition, English volume

Projection period

Multilingual Demographic Dictionary, second unified edition, English vol.
Jump to: navigation, search
Projection period  (PROJECTION period)

Population projections 1 are 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. A population forecast 2 is a projection in which the assumptions are considered to yield a realistic picture of the probable future development of a population. Although the projection period 3 is variable, short-term forecasts 4 are the rule, as the margin of error to which forecasts are subject increases considerably as the length of the forecast’s period increases. The most frequently used method of projection is the component method 5 or cohort-component method 5 which takes the population distributed by age and sex at a base date 6 and carries it forward in time, cohort by cohort, on the basis of separate allowances for fertility, mortality and migration. When matrix algebra is used for component projections, the method is sometimes called matrix method of projection 7.

  • 1. Projections are also made in terms of educational, economic and social characteristics. Backward projections which might be more accurately called retrojections, use similar methods to trace the past evolution of the population.