Demography, sources and availability of demographic data


Demography is the statistical study of human populations. Demographic characteristics of a country provide an overview of its population size, composition territorial distribution, changes therein and the components of changes such as nativity, mortality, and social mobility.

Demography is important for town planners due to need of forecasting and planning for the people. People are the ones for which planning is being carried out. Indirect methods of collecting data about demography are required in countries and periods where full data are not available, such as is the case in much of the developing world, and most of historical demography.


This section on demographic indicators has been subdivided into two parts-

Population Statistics Vital Statistics
Population size,Sex ratio,Density and dependency ratio Birth rate,Death rate,natural growth rate,Life expectancy at birth,Mortality and fertility rates

These indicators for the country, state as well as district will help in identifying areas that need policy and programmed interventions, setting near and far-term goals, and deciding priorities, besides understanding them in an integrated structure.

Table showing sub aspects their indicator with unit:

Data indicator Unit
Population No. of persons
Population density Persons per sq. km.
Sex ratio Number of females per 1000 males
Age structure of population %
Age-specific sex ratios Number of females per 1000 males
Dependency ratio Population under age 15 (0-14 years) +Population aged 60 years and above)——————————————————-   * 1000 Population between age 15 and 59 years
Crude birth rate number of live births occurring during the year, per 1,000 population estimated at midyear.
Crude death rate number of deaths occurring during the year, per 1,000 population estimated at midyear
Natural growth rate CBR- CDR
Total fertility rate average number of children that would be born to a woman over her lifetime
Infant Mortality Rate Number of deaths under 1 year in a year————————————————          * 1000 Number of live births in the same year
Maternal mortality rate the number of maternal deaths per 1,000 women of reproductive age in the population
Net Migration rate Net migration during a specified time period in an area ————————————————————-  * 1,000 Area’s population at the  mid point of the same time period
Life expectancy at birth number of years a newborn infant would live if prevailing patterns of mortality at the time of its birth were to stay the same throughout its life.

Sources and availability of demographic data

Three main sources

  1. Population Census- A census is a count of the age and sex of all people in a specified territory at a given time. A census may also collect other demographic, social and economic information.
  2. Surveys-  A survey attempts to describe, as accurately as possible, the demographic aspects of a population by collecting information on a sample of the total population.
  3. Vital Statistics System- Vital statistics system refer to the registration of births and deaths in a population.