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# Composition of Population Making Population Pyramids.

## Presentation on theme: "Composition of Population Making Population Pyramids."— Presentation transcript:

Composition of Population Making Population Pyramids

Composition Ages and sex of the members of the population Population pyramids divided into male and female data according to age- each section is called a cohort Cohorts are usually in 5 year intervals Eg. 0-4 years old- 4.3 million females, 3.6 million males 5-9- 3.7 million females, 2.8 million males

Population Pyramids Data from cohorts can be graphed using the age-sex technique which will usually take on the shape of a pyramid

Central vertical axis is cohorts stacked on top of one another (youngest – oldest) Bars on the left of the vertical axis indicate males (% of pop.) Bars on the right of the vertical axis indicate females (% of pop.)

Classifying Population Pyramids Pyramids can be classified as… –Expansive- countries with high birth rates but death rate that is declining rapidly

Stationary- countries where both birth and death rates are low

Dependency Ratio Based on the assumption that certain age cohorts do not work (very young and very old) They depend on others for financial support Working age group considered b/w 15-64 years old

Dependency ratio = % people under 15 + % people over 64 % potential labour force (15-64) Eg. Canada in 1961 Dependency ratio = 33.8 + 8.4 57.8 = 0.73 Meaning, each potential labour force person supports themselves plus 0.73 additional people

Demographic Transition Model Birth and death rates tend to go through a sequence of predictable changes Given the same factors of economic and social development; all countries go through the same changes in their birth and death rates

4 stages of the transition model 1.High birth rate and high death rate, low natural increase - the population grows slowly 2.High birth rate and decreasing death rate, large natural increase - rapid growth in population 3.Both birth and death rates are falling, still large natural increase - population still growing, but at a slower rate 4.Low birth and death rate, low natural increase, slow population growth

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