The study of population is of major concern to sociologists and social scientists. To sociologists, population is the number of persons occupying a certain geographic area, drawing substance from their habitat, and interacting with one another.

Demographers commonly define population as a collective group of individuals occupying a particular place at a given time. Three key words are involved in the definition, namely: group, place, and time. Thus, in getting the population of a country, one takes the total population, not individually; includes all places within the geographical limits; and specifies the time when the population count is done. Thus persons who are not part of a collective group, who are not situated within the geographical limits and who are not living, or who have died during the time of the population count are definitely not included in the so-called population.

Population growth is a major factor in energy consumption, housing shortages, inflation, food security, unemployment and environmental degradation. Many scientists warn that unchecked population growth threatens to consume an already compromised store of the world’s resources.

Population growth has been and will continue to be an integral part of our lives. It accounts for the emergence and intensification of many local, natural and global problems like poverty and inequality, energy crisis, malnutrition and scarcity or food supply, housing problems, criminality, economic crisis, and environmental degradation; the world’s already depleted resources currently threatened by an unchecked population growth. The countries of the South and the 3rd world countries are experiencing internal factors like internal bickering, massive poverty, graft and corruption, economic and political crisis. It is also a fact that there is rapid population growth among these countries of the world.

In their book, Collins Dictionary of Sociology. David and Julia Gary define demography (from the Greek “demos”, people) as the statistical study of human populations with regard to their size and structure, their compositions by sex, age, marital status and ethnic origin, and the changes to these populations like changes in their birth rates, death rates and migration. Demography is the statistical analysis and description of population aggregates with reference to the distribution, vital statistics, age, sex and related factors.

The science of demography looks also into the factors that may cause population to increase or decrease in any given area. It is concerned with numbers and quantities and the relation between them. Demographers use the statistical method in their analysis of demographic data.

Demographers gather, collate, and analyze population data and make a technical presentation of theory. Petersen defines demographers as people who gather data about the size, distribution, composition, and change in population in order to describe them.

Demography has the following primary tasks:

  1. To ascertain the number of people in a given area.
  2. To know the resources available for their support.
  3. To determine what changes, growth or decline this number represents and explain the cause (s) of the changes.
  4. To estimate on this basis the future trends
  5. To know the different kinds of people who may make up any given population with regard to their physical, mental and cultural characteristics.
  6. To categorize people on the basis of characteristics like age, sex, marital status, occupation, income, nationality, race, ethnic group, religion and other characteristics.
  7. To ascertain the distribution of people among the different countries and regions, both rural and urban.
Importance of Demography and Demographic Data

Citing the importance of demographic data, the Programme of Action of the United Nations International Conference on Population and Development, Cairo 1994, states: “The everyday activities of all human beings affect community patterns and levels of use of natural resources, the state of the environment, and the pace and quality of economic and social development.

Numbers of people are always a significant correlate of social life; during times of famines and epidemics or on frontiers and in newly settled territories, they can become decisive for progress or decline.

Demographic data provide a basis for predicting future trends and making informed decisions. As Panopio states, demographic data are important for the formulation, implementation, and evaluation of plans, policies, and programs for education, housing, health, employment, transportation, recreational needs and other forms of social services. Demographic data can guide policy makers in meeting the needs of various sectors of the society, such as the young, the adult and aged, the unemployed, the poor, and the various cultural group.

Sources of Demographic Data

There are varied sources of the population’s composition and distribution. The main sources of demographic data are:

  1. Population Censuslike population count.
  2. Vital registration statistics system like birth, death, marriage, and divorce.
  3. Sample or Special Surveys like surveys of households; and
  4. Demographic data gathered and processed by government agencies.