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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