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Geography

Population change and structure

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# Causes and rates of change

## The three main causes of population change

• Births - usually measured using the birth rate (number of live births per 1,000 of the population per year).
• Deaths - usually measured using the death rate (number of deaths per 1,000 of the population per year).
• Migration - the movement of people in and out of an area.

## Rate of change

Births and deaths are natural causes of population change. The difference between the birth rate and the death rate of a country or place is called the natural increase. The natural increase is calculated by subtracting the death rate from the birth rate.

natural increase = birth rate - death rate

The rate of natural increase is given as a percentage, calculated by dividing the natural increase by 10. For example, if the birth rate is 14 per 1,000 population, and the death rate is 8 per 1000 population, then the natural increase = 14 - 8 = 6. That is 6/1000, which is equal to 0.6 per cent.

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