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