Unit Three‎ > ‎

Demographic Trends

Demography is the study of human population statistics. It allows those who study it to predict the movements of groups of people and the expected increase and decrease in the population size.

The four main Factors that change the population size are Birth rate, Death rate, Immigration rate and emigration rate. The birth/death rate is the annual number of birth/deaths per 1000 population. The emigration/immigration rate is the emigrants/immigrants per 1000 population.

Graphs are often used to clearly convey the trends of an area. However for the sake of simplicity, the Immigration rate and emigration rate is often assumed to be equal.

Comparing a developing and a developed country 


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In a developing country the death rate is decreasing more rapidly than the birth rate. Therefore the difference between the two is increasing which leads to the population growth rate increasing.
However, in a developed country the opposite is occuring. The birth rate is decreasing more rapidly than the death rate so that the population growth rate is slowing down.
Demographic Transition Model
This model attempts to relate the rate of population growth with cultural development . It suggests that a developing country gradually becomes developed (Industrialized) There are four demographic stages represented by the following equations.
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        1.    high br + high dr                                  stable population
        As both birth and death rates are approximately equal, population growth is slow
        or non - existent
        2.     high br + moderate dr                     early expansion in population
        Since the birth rate now exceeds the death rate, poulation growth (sometimes
        rapid) occurs.
        3.    moderate br + low dr                        late expanding population 
        The difference between birth rate and death rate is now smaller than before, as a
          4.    low br + low dr                                       stable population
        Birth rate and death rate now cancel each other out, resulting in slow or non - 
           non - existent population growth non - existent population growth.
        The transition from a developing country to a developed country involves a large
        rise in population.
Population pyramids

Are used to represent the structure of a population in respect to age and sex of the group. Both developing and developed countries have distinctive shapes to their respective pyramids. 
Pyramids are often used to help in the anticipation of future needs. In some cases, the needs of the future like (health facilities, transport and education)
The gender balance or imbalance is also a is also a feature