Demography may be defined as the science which deals with the study of all aspects of population progress, welfare, death in a family, birth in a family, age and number of children, number of school going children, their educational qualifications; sickness, deformities in the family and sanitation etc. It also includes the study of standard of living as well as property held.
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The other terms used in place of demography include ‘population dynamics’ and ‘population studies’.
The main sources of demographic data include vital registration system of births and deaths and census.
From these demographic studies many statistical conclusions can be drawn as given below:
1. Population of the country in any particular year.
2. Birth rate.
3. Death rate.
4. The difference between birth rate and death rate results in addition to the net population every year.
5. Men-women ratio, married and unmarried.
6. Per capita income.
7. Per capita agriculture land.
8. Nourishment and undernourishment data.
9. Literacy rate.
10. Density of population per sq. km.
11. The distribution of urban and rural population.
12. Religious composition.
13. Life expectation data.
From census studies it is found out that about 80% of the world’s population is living in the developing countries and the remaining 20% of the world’s population is living in developed countries. According to history of population the population growth takes place according to a cycle known as demographic cycle. This cycle is divided into following stages:
(a) High Stationary Stage:
It is the first stage during which the population remains stationary because there is a high birth rate as well as high death rate which cancel each other hence the population remains stationary.
(b) Early Expanding Stage:
It is the second stage during which the death rate begins to fall but the birth rate remains unchanged so there is increase in the population. Most of the developing countries like India fall in this stage.
(c) Late Expanding Stage:
It is the third stage during which the birth rate decreases but still the population continues to increase because the birth rate is still higher than the death rate.
(d) Low Stationary Stage:
It is the fourth stage during which the population remains almost stationary because there is low birth rate as well as low death rate. Developed countries like America fall in this stage.
(e) Declining Stage:
It is the fifth stage during which the population begins to decrease because the birth rate is lower than the death rate.