Reasons why the census data important is for a country.

Uses for policymaking, planning and administrative purposes

The fundamental purpose of the population census is to provide the facts essential to national policymaking, planning and administration. Information on the size, distribution and characteristics of a country’s population is essential for describing and assessing its economic, social and demographic circumstances and for developing sound policies and programmers aimed at fostering the welfare of a country and its population. The population census, by providing comparable basic statistics for a country as a whole and for each administrative unit, locality and small area therein, can make an important contribution to the overall planning process and the management of national affairs. Counts of the population overall, or of subgroups within the population, by geographic region are often used for the distribution of government funding and services. Population censuses in many countries represent the very foundation of their national statistical systems, with census data providing important baseline data for policy development and planning, for managing and evaluating programme activities across a broad range of sectoral applications, and for monitoring overall development progress. An emerging use for census data is the assessment of good governance by civil society groups. The performance of a democratically elected government in improving the welfare of its citizens can be monitored from one census to the other by ordinary citizens through the widespread and timely dissemination of census results. 

Population censuses serve many programme needs by providing statistical information on demographic, human settlement, social and economic issues for local, national, regional and international purposes. For example, population censuses provide basic information for the preparation of population estimates or projections and detailed demographic and socioeconomic analysis of the population. The census also provides data for the calculation of social indicators, particularly those that may be observed infrequently because they measure phenomena that change slowly over time, and those that are needed for small areas or small population groups.

Uses for research purposes

In addition to serving specific governmental policy purposes, the population census provides indispensable data for the scientific analysis and appraisal of the composition, distribution and past and prospective growth of the population. The changing patterns of urban–rural concentration, the development of urbanized areas, the geographic distribution of the population according to such variables as occupation and education, the changes in the sex and age structure of the population, and the mortality and fertility differentials for various population groups, as well as the economic and social characteristics of the population and the labour force, are questions of scientific interest that are of importance both to research and for solving practical problems of industrial and commercial growth and management.

Uses for business, industry and labour

In addition to those uses given above, the census has many important uses for individuals and institutions in business, industry and labour. Reliable estimates of consumer demand for an ever‐expanding variety of goods and services depend on accurate information on the size of the population in subnational areas and its distribution at least by sex and age, since these characteristics heavily influence the demand for housing, furnishings, food, clothing, recreational facilities, medical supplies and so forth. Furthermore, the census can be used to generate statistics on the size and characteristics of the supply of labour needed for the production and distribution of such commodities and services in conformity with International Labour Organization statistical standards.15 Such statistics on the local availability of labour may be important in determining the location and organization of enterprises.

Uses for boundary delimitation

One of the basic administrative uses of census data is to support political and administrative mapping. Detailed information on the geographic distribution of the population is indispensable for this purpose. Certain aspects of the legal or administrative status of territorial divisions may also depend on the size and characteristics of their populations, for example, whether a previously rural area is now to be declared as urban.

A compelling use of census data is in the redrawing of electoral constituency boundaries in most countries. This is often enshrined in the country’s constitution and provides a legal basis for census taking. The current distribution of a country’s population is thereby used to assign the number of elected officials who will represent people in the country’s legislature.

Use as a sampling frame for surveys

Population censuses constitute the principal source of records for construction of a sampling frame for surveys during the intercensal years on many topics, such as the labour force, fertility and migration histories.