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Demography Part I

Demography Part I. What is demography?. Demography = The study of human populations. Figure from: http://www.ecofuture.org/pop/facts/exponential70.html. I. Measures of growth:. Crude birth rate (CBR) = Number of live births per 1,000 people in a given population per year

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Demography Part I

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  1. Demography Part I

  2. What is demography? Demography = The study of human populations Figure from: http://www.ecofuture.org/pop/facts/exponential70.html

  3. I. Measures of growth: • Crude birth rate (CBR) = Number of live births per 1,000 people in a given population per year • Crude death rate (CDR) = Number of deaths per 1,000 people in a given population per year  Example: The average world CBR in 2000 was 22 and the average CDR was 9. *** Both CBR and CDR are usually express as number, with the “per thousand” assumed.

  4. II. Fertility: • Total fertility rate (a.k.a. fecundity; TFR) = an estimate of the number of children a woman will produce over her lifetime if she follows patterns of the current year

  5. Replacement-level fertility = number of children a couple must bear to replace themselves What do you predict about replacement level fertility in more developed nations compared to developing nations?

  6. III. What increases populations? • Fertility/Birth Rate • Immigration = people moving in  Displaced by war, natural disasters, environmental damage, economic hardship

  7. What affects birth rates? • Importance of children in workforce • Rural vs. Urban • Governmental structures/agencies/programs • Costs of raising children • Educational/employment opportunities for women • Infant mortality rate • Average age of women at first childbirth • Average marriage age • Availability of pensions • Availability of birth control/abortions • Economic status • Religious and cultural beliefs

  8. IV. What decreases populations? • Death • Emigration= people moving elsewhere (same reasons as immigration—war, famine, natural disasters, environmental damage, economic hardship)

  9. What affects death rates? • Improvement in medicine/public health • Improved sanitation, hygiene • Availability of insecticides • Safer water supplies • Better nutrition • More food/better food distribution • Diseases (e.g. AIDS) • Increased violence • Natural disasters

  10. Eastern Europe & Central Asia 58 000 [41 000 – 88 000] Western & Central Europe 8000 [4800 – 17 000] North America 23 000 [9100 – 55 000] East Asia 40 000 [24 000 – 63 000] Middle East&North Africa 27 000 [20 000 – 35 000] Caribbean 14 000 [11 000 – 16 000] South & South-East Asia 340 000 [230 000 – 450 000] Sub-Saharan Africa 1.5 million [1.3 – 1.7 million] Latin America 63 000 [49 000 – 98 000] Oceania 1000 [<1000 – 1400] Estimated adult and child deaths from AIDS, 2007 Total: 2.0 million (1.8 – 2.3 million)

  11. V. Calculating Population Change In general: Population Change = (birth + immigration) – (death + emigration) Simpler calculations can be achieved by neglecting migration, or wrapping migration into CDR/CBR: Change = (Births – Deaths) R (in %) = Annual rate of natural population change R = (CBR / 1,000 people – CDR / 1,000 people ) X 100 R = (CBR – CDR) / 10

  12. PRACTICE CALCULATIONS CBR = 15, CDR = 10 CBR = 9, CDR = 10 CBR = 40, CDR = 20

  13. So why has the world population been growing?? a. People in developing countries having more and more children (i.e. higher birth rates) b. Decrease in the death rates with improved medicine/public health c. Worldwide increase in birth rates, with the exception of Europe. d. Both A and B. e. Both A and C. f. All of the above.

  14. So why has the world population been growing?? • Decline in death rates over the past 100 years is sole reason. • In 1950’s the TFR for women in developing nations was 6 children…today the average is 3.1. Birth rates are falling but not as fast as death rates!

  15. VI. ZPG • Zero population growth= population size remains stable • Birth + Immigration = Death + Emigration • R = 0 % Time lag for ZPG? Because of the age structure of populations… • 70 to 100 years for population to stabilize once fertility rates have dropped to or below replacement levels  Population Momentum

  16. VII. Age structure of populations (a.k.a. population pyramids) • Age Structure: The proportion of a population at each age level. Usually the whole population of an area of interest is displayed as percent (or total number) males and females in 5-year age categories. • There are 3 basic age structures: • Expansive (rapid growth) • Stationary (slow/no growth) • Regressive (negative growth)

  17. Population Pyramids—which is which? Images adapted from: http://www.health.state.pa.us/hpa/stats/techassist/pyramids.htm

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