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An introduction to population pyramids
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What it is and how it works
Canada 1961
Consists of two back-to-back bar graphs
population plotted on the X-axis and age on the Y-axis, in five-year age groups (cohorts).
Males are shown on the left and females on the right
Measured by raw number or as a percentage of the total population.
Canada 1961
Where are you represented? Males? Females?
Oldest at top Youngest?
Each age group called a “cohort”
Stationary narrow base and
roughly equal numbers in each age group, tapering off at the older ages.
Scandinavian countries
Expansive broad base rapid rate of population
growth low proportion of older
people. A steady upwards
narrowing shows that more people die at each higher age band.
This type of pyramid indicates a population in which there is a high birth rate, a high death rate and a short life expectancy.
LLDC’s for the most part
Constrictive- a high proportion
of aged persons and declining numbers.
- Germany, Italy
Used to find the number of economic dependents in a population. Under 15 (those in k-12 full time, unable to work) and over
65 (those who have the option of retirement)
Dependency ratio = % under 15 + % over 64% 15-64
Used to observe natural increase, birth/mortality rates, breakdown by age range within a population
What do you notice about this pyramid?
Why do you think there is a “bulge” in the middle?
Notice the bottom 3 age groups – why is it that they are the largest?