Need and Uses of Population Estimates

In demography, population estimation and projection method are so intertwined that together form one separate field of scientific endeavor. Population estimation provides quantification of population facts not obtained by other methods like census and surveys. A population projection may be defined as the numerical outcome of a specific set of assumptions regarding future trends in fertility, mortality and migration. 

Need and Uses of Population Estimates

In ancient days the population estimates were needed for the purpose of ascertaining the supply for the military forces, for assessing number of persons who could be slave and the number of persons who could be taxed etc. The function of the present day governments have become increasingly complex but more plan-oriented. For the planning of socio-economic and welfare activities, we need a fairly accurate knowledge of the size of the country’s population, its rate of growth, its spatial distribution, its age sex composition, educational groups and various other characteristics. The population estimates and projections are equally important for the governments as well as private agencies. The researchers too require the population projection as an analytic too to experiment with demographic process for better understanding of the population dynamics. They permit experiments out of which we obtain causal knowledge; they explain data; they explain data; they focus research by identifying theoretical and practical issues; they systematize comparative study across space and time; they reveal formal analogies between problems that on their surface are quite different; they even help assemble data” (Keyfitz, 1971).

Projection of a population in future is the manifestation of facts and assumptions that we make. While analysis of population data in the past enables us to comprehend the population dynamic; the knowledge of the current data helps us to understand and foresee the future course of the population change. Thus with the knowledge of present facts on population and assumption regarding the future course of change projection provide a link between the past, the present and the future. Hence the population projection virtually becomes result of speculations which are based on the trends in demographic indicators established by the past.