Michael Metz 10-8-11 Chapter 2, Key Issue 3 Why is Population Increasing at Different Rates in Different Countries? The Demographic Transition What are the stages of Demographic Transition? The demographic transition is a process that has a beginning, middle, and end. Historically, once a country progresses from one stage to the next, it does not revert back to an earlier stage. Stage 1: Low growth High CBR High CDR Very low NIR Stage 2: High Growth High CBR Lower CDR High NIR Stage 3: Moderate Growth Lower CBR CDR remains the same Lower NIR (still positive) Stage 4: Low Growth CBR and CDR are essentially equal Zero population growth Population Pyramids How is a population Pyramid?s shape determined? In what 2 ways are population influenced by the demographic transition? The shape of a population pyramid is determined based on the CBR in the community. The age structure of a pyramid is important in knowing similarities and differences among countries. Most important factor is the dependency ratio. The sex ratio is also important in determining the number of males and females in a country. Countries in different stages of the Demographic Transition Countries show distinctive population traits depending on their stage in the demographic transition. Demographic Transition and World Population Growth Worldwide population increased rapidly in the second half of the 20th century (Baby Boomers) Vocabulary: Demographic Transition- A change in a society?s population Agricultural Revolution- Time when humans first domesticated plants and animals and no longer relied entirely on hunting and gathering Industrial Revolution- A conjunction of major improvements in industrial technology. Medical Revolution- Improved medical practice Zero population growth- term often applied to stage 4 countries Population Pyramid- Shows the percentage of the total population in 5 year groups, Dependency Ratio- The number of people who are too young or too old to work. Sex Ratio- Number of males per hundred females in the population .
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