Population Projection

Population projection is an estimate of the population size in the future. Estimation of population is important since it helps policymakers and researchers in decision-making for resource allocation and intervention measures. An estimate is a calculation of the size and distribution of a population or another characteristic of the population for the present or past, while projection describes these characteristics in the future. Population projection is the computation of future changes in population numbers, given certain assumptions about future trends in the rates of fertility, mortality, and migration—the key demographic processes. A population projection gives a picture of what the future size and structure of the population by age and sex might look like. Population projection is calculated based on the baseline population size and a number of other variables such as population growth rate, migration, and mortality. In this chapter, the scope, uses, and public health importance of population projection, assumptions, and methods will be described. A few examples of simple methods of population projection have been provided.