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Canada (162,055)
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SOC101Y1 (470)
Chapter 4

Chapter 4: Demographic Composition

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Blair Wheaton

Chapter 4 Demographic Composition Under 15, age 15-64, 65+: By looking at these three sectors, scientists can determine the economic dependency burden in a society. The ratio of youth plus old-age dependents to the working population gives a measure of a society's overall dependency on the workers. If a society has a high youth dependency ratio, its old age dependency ratio will be low. Age Pyramids: Pictorial representation of age and sex compositions. Canada's age pryamid: Bulge associated with baby boom. The people over 65 is increasing while the 15 and under cohort is declining. General typology of age pyramids: TYPE A: Rapidly growing populations have wide base and narrow top. Africa, Asia, Central America. TYPE B: Age structure remains constant. Represents a stationary population with a constant rate of growth. No population currently reflects this type. TYPE C: Countries that have completed the demographic transition. Western countries. Age distribution is top-heavy and the base is narrow. Declining population. Fertility is the major determinant of age composition. Varying mortality while holding fertility constant has little effect on age distribution. A young population is produced by high fertility rates. Declining fertility produces an aging population. However, prolonging life by reducing death rates makes the population somewhat younger because reduced mortality affects young people as well, so more people live to child-bearing years, and more births would occur. Stable population model: Stable populations can either increase or decrease in size, as long as the rate of change remains constant - what is stable is the shape of the age distribution. A stationary population is a type of stable population in which the rate of growth is zero; the size nor the age structure changes. Allows us to explore "what if" scenarios. If a researcher assumes constant age-specific birth and death rates in a real population, they can determine how this will later affect age distribution in the future. Crude and Intrinsic growth rates: RNI is the difference between the crude birth and death rates for a given population. Rate of natural increase based on crude rates does not take into account current age compositions, so the result is a crude measure of the rate of growth. A net rate of natural growth can be computed, known as the instrinsic rate of growth which measures the rate of growth without the confouding effects of age composition. Industrialized countries would show negative intrinsic growth rates because of the low fertility combined with low death rates. The reason these populations are showing positive crude rates is because their age compositions reflect the effects of high fertility rates in the past. How does migration affect age-sex structure? Migration tends to be negligable compared to the effects of birth and mortality change. However it can make an impact if the numbers emigrating are large and concentrated in a specigic age/sex category. In Canada, the age pyramid of the immig
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