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Planning and Demography

Planning and Demography.

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Planning and Demography

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  1. Planning and Demography • Demography is the scientific study of human population. Demographers are very interested in: 1) Population size, 2) Population composition, 3) Population distribution, 4) Causes of changesin these factors over time, 5) Consequences of these changes over time. • Demographers study in detail these changes over time, investigating issues such as changes in fertility rates, mortality rates, and migration. • Planners are also very interested in these very same issues, but from a perspective of: --how do population changes influence the demand for and provision of infrastructure and public services --how will population changes impact the environment --how do population changes influence changes in land use

  2. Population Size • Population size: The number of people in a given geography at a given time. U.S., Florida, and Leon County Population 1960-2000 US FL LC • Natural Increase: The amount of population increase attributable to a greater number of births than deaths. --In US in 1990, 17 births per 1000, 9 deaths per 1000 a natural increase of 8 per 1000 (0.8%) (290 million) --World  1.8% per year for natural increase (6.26 billion) • Use the “Rule of 70” to determine doubling time: Divide 70 by the growth rate. So World will double population in ~39 years (70/1.8 = ~39)

  3. Population Distribution • Population distribution: The location of population across geography/space. • Major shifts in population distribution occurred in the Twentieth Century in the United States: • --Concentration: Movement from Rural to Urban/Metro Areas • --Deconcentration: Movement from Central Cities to Suburbs • --Migration from the Rust Belt to the Sun Belt • Planners are particularly interested in these changes and their impacts on the built and natural environments. • These macro-level changes have tremendous impacts upon communities of all sizes and in all areas of the United States.

  4. Concentration Illustrated Roughly 4 of every 5 Americans lives in a metropolitan area now.

  5. Deconcentration Illustrated As of 2000, 1 of every 2 Americans lives in a suburban area.

  6. Regional Shifts Illustrated

  7. Regional Shifts Illustrated

  8. Population Composition • Population composition: The characteristics of the population. • Among those characteristics of interest to demographers and planners are: --Age --Sex --Race/Ethnicity • Again, the United States experienced many changes in these attributes throughout the Twentieth Century: --An aging population --The “rise of women” --An increasingly racially and ethnically diverse population

  9. An Aging Population Illustrated

  10. An Aging Population Illustrated

  11. The “Rise of Women” Illustrated

  12. A Diversifying Population Illustrated

  13. A Diversifying Population Illustrated

  14. Population Pyramids • One way of looking at changes in the composition of a population is through Population Pyramids. • Population pyramids show the composition of a population by age and sex (percent population in all age-sex cohorts) • These pyramids typically show the following: • --Males on left side/Females on the right side • --Age groups as individual cohorts going from youngest on the bottom to oldest on the top • These pyramids can be done for different geographies and/or different racial and ethnic groups.

  15. U.S. Population Pyramids 1900, 1950, 2000

  16. Florida’s Population Pyramid, 2000

  17. Franklin County Population Pyramid, 2000

  18. Leon County Population Pyramid, 2000

  19. Measuring Population Change • Population change is simply the difference in population between two points in time. • Change can be expressed in Absolute or Percentage terms. • Absolute Change: The simple difference between population figures. Negative values indicate a loss in population. • Florida’s Absolute Population Change 1990-2000Pop 2000 – Pop 1990 15,982,378 – 12,937,926 = 3,044,452 • Percent Change: The relative growth rate over a period of time calculated as a percentage using the formula: [(New-Old)/Old] *100 • Florida’s Percent Population Change 1990-2000 (Pop2000-Pop1990)/Pop1990*100 • (15,982,378- 12,937,926) 12,937,926 * 100 = 23.53%

  20. Example Percent Population Change Analysis U.S., Florida, and Leon County Population Change 1960-2000 U.S. %Chg Florida %Chg Leon Co %Chg • Florida and Leon County grew at much faster rates than the United States as a whole during the period 1960-2000. • Leon County’s growth mirrored that of Florida’s during this period.

  21. Migration Mortality Fertility Components of Population Change • Demographers rely upon the “Demographic Balancing Equation” to very simply and elegantly summarize population change: • Pop2 = Pop1 + B – D + IM – OM, where • Pop2 = Population at a later time period • Pop1 = Population at an earlier time period • B = Births • D = Deaths • IM = In-Migration • OM = Out-Migration • The nature of population change is simple… changes can only occur through: 1) Births, 2) Deaths, or 3) Migration

  22. Fertility Component • Fertility: The number of births that occur to an individual or in a population.  • Fecundity: The physiological ability of individuals or couples to have children. Maximum fecundity for a population is believed to be 15 children. • Another key concept is the “at-risk population”. Only a certain subset of the population is “at-risk” for fertility  Women aged 12-50 • Factors that affect fertility include: 1) Gender (Duh!) 4) Socioeconomic status 2) Age 5) Others Religion, Culture, Education 3) Race/Ethnicity • Common calculations related to fertility include:1) Total Fertility Rate: Average # of children in a “synthetic” family2) General Fertility Rate: #Births per 1000 women of childbearing age3) Crude Birth Rate: # Births/Midyear Population

  23. Mortality Component • Mortality: Analyzes the number and causes of deaths in a population. • Life Span: The upper limit to human lives is theorized to be somewhere around 120, although there are reports of some people living as long as 135 years. • Factors affecting mortality include: 1) Age (J-curve) 4) Race/Ethnicity 2) Gender 5) Modernity 3) Socioeconomic status • Common calculations related to mortality include:1) Overall Death Rate: Deaths per 1000 population2) Crude Death Rate: # Deaths/Midyear Population3) Age-Sex-Race specific survival rates: The likelihood that an individual with certain characteristics will survive the year 4) Life Expectancy: The expected number of years an individual will live if they were to live their entire life right now. In 1900~30 (worldwide) By 2000~70 (worldwide)

  24. Theory of the Demographic Transition • When taken together, mortality and fertility can combine to form four scenarios: • It is theorized that as countries move from less developed to more developed, they transition from a High Birth/High Death society to one of Low Birth/Low Death. It is during this transition that (it is theorized) developing countries experience a population boom. Why?

  25. Migration Component • Migration: The movement of people into and out of a certain area. • Migration can occur at all geographic levels. 1) Neighborhood 2) Within a county 3) Across states: Out-migration versus In-migration 4) To a different country: Emigration (out of a country) versus Immigration (into a country) • Migration in the United States:Approximately 20% of Americans move per year Americans move about 11 times over their lifetimes (on average) • Factors affecting migration include 1) Age 2) Gender 3) Socioeconomic Status 4) Race and Ethnicity

  26. Major State to State Migration Flows

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