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Composition of Population Making Population Pyramids.

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

1 Composition of Population Making Population Pyramids

2 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

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

4 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.)

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

6 Stationary- countries where both birth and death rates are low

7 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

8 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

9 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

10 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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