Sunday, 5 May 2013

DEMOGRAPHIC TRANSITION


Demographic transition developed by an American demographer Warren Thompson observes changes in the birth and death rates in industrialized societies over previous 200 years. But like all models the demographic transition model has its limitations.

  • It does not consider the influence of migration. Both immigration and emigration.
  • There is no time scale present. 
  • The death rates in Germany and Sweden are higher than the birth rates indicating that there might be a fifth stage present.
  • It does not consider the effect of female literacy and employment on population.
  • Based on the change in population of UK and might not be applicable for all the countries.
  • Influence between countries like war is not considered. 


Stages of Demographic Transition:




As we can see in the above figure there are four stages:

Stage 1- High Fluctuating Period:

  • Both death rates and Birth rates high.
  • Lack of disease control, famine, poor hygiene lead to very high death rates.
  • The need for more man power and many religious beliefs lead to high birth rate.
  • As both death and birth rates are high the increase in population is less in this period.
Stage 2 – Early Expanding: 

  • Various medical science advances in this period lead to decrease in Death rate with birth rate being the same.
  • This resulted in increase in population in this era. 
Stage 3 – Late expanding:

  • Birth rates are decreased due to various factors such as government policies, increasing cost to raise a child, higher literacy among females contributed to this.
  • Here the population is still increasing but the rate of increase has been reduced. 
Stage 4 – Low Fluctuating:

  • Both birth rates and death rates are low and of the same value resulting in the stabilization of the population. 


Uses of DTM:

  • It helps us to predict the future population of a country and how it would change overtime.
  • Comparison between two countries can help us find out how economic and social conditions might affect the population. 

POPULATION PYRAMIDS

A population pyramid, also called as age picture diagram, is a graphical illustration hat shows the distribution of various age groups in a population which forms the shape of a pyramid when the population is growing.



Above is the population pyramid of the world in 2010.The features of a population pyramid are 

  • Male figures are to the Left of the pyramid and female figures are to the Right of the pyramid. 
  • The horizontal axis may either represent the actual number or the percentage of the total population in each age category. 
  • The vertical axis is divided into various age groups known as Cohorts. 

Uses of a population Pyramid:

  • The division between the sexes can be analyzed. 
  • A wider base indicates a higher youth population as a result of high birth rates. 
  • A narrow top indicates that there are fewer people in older age group as a result of low life expectancy. 
  • Dependency can be calculated knowing the population pyramid. 
  • A Column shaped population pyramid indicates a nation in stage 4 of demographic transition with equal death and birth rates. 
  • The level of immigration can also be shown in the population pyramid.




India's Demographic Stats

Data from SRS and Census are widely used for assessing on going demographic transition in the country. Census provides data once in ten years. The Sample Registration System (SRS) was established in order to provide dependable annual, state-specific data. The SRS was initiated by the Office of the Registrar General, India on a pilot basis in a few selected states in 1964-65. It became fully operational during 1969-70.

A comparison of some demographic parameters between India and some of the neighboring countries is given in Table 2.1. China and Sri Lanka are far ahead of India in all these parameters.


Some Demographic Parameters : India and It's Neighbors 



Time trends in some of the major demographic indices are shown in the following table.


India - Selected Health Indicators




Demographic Transition in India






Population Projections


The population pyramids for 2001 and 2026 are shown in the figures below. The average age of Indians was 23 in 2001 and is expected to rise to 31 years old in 2026.


Projected population (India 2001)


Projected population (India 2026)




The substantial interstate differences in age structure and consequently population pyramid will persist even in 2026 because different states have achieved fertility and mortality transition at different rates. These have to be taken into account while planning nutrition and health interventions in these states.



Projected population (Kerala 2026)



Projected population (Uttar Pradesh 2026)





The results of the last two censuses, especially the findings of the 2011 Census, clearly indicate that the country has entered the last phase of demographic transition, usually characterized by rapidly declining fertility. The crucial question now is — how long will this phase extend and when will India achieve a stable population?

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