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Planning and Demography


Planning and Demography Demography is the scientific study of human population. Demographers are very interested in: 1) Population size, 2) Population composition, – PowerPoint PPT presentation

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Title: Planning and Demography

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 changes in these factors over
    time, 5) Consequences of these changes over
  • 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

Population Size
  • Population size The number of people in a given
    geography at a given time.
  • U.S., Florida, and Leon County Population
  • 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)

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.

Concentration Illustrated
Roughly 4 of every 5 Americans lives in a
metropolitan area now.
Deconcentration Illustrated
As of 2000, 1 of every 2 Americans lives in a
suburban area.
Regional Shifts Illustrated
Regional Shifts Illustrated
Population Composition
  • Population composition The characteristics of
    the population.
  • Among those characteristics of interest to
    demographers and planners are --Age --Sex
  • 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

An Aging Population Illustrated
An Aging Population Illustrated
The Rise of Women Illustrated
A Diversifying Population Illustrated
A Diversifying Population Illustrated
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

U.S. Population Pyramids 1900, 1950, 2000
Floridas Population Pyramid, 2000
Franklin County Population Pyramid, 2000
Leon County Population Pyramid, 2000
(No Transcript)
Measuring Population Change
  • Population change is simply the difference in
    population between two points in time.
  • Change can be expressed in Absolute or Percentage
  • Absolute Change The simple difference between
    population figures. Negative values indicate a
    loss in population.
  • Floridas Absolute Population Change
    1990-2000 Pop 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
  • Floridas Percent Population Change
    1990-2000 (Pop2000-Pop1990)/Pop1990100
  • (15,982,378- 12,937,926) 12,937,926

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 Countys growth mirrored that of Floridas
    during this period.

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

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
  • 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)
  • Common calculations related to fertility
    include1) 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

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
    include1) Overall Death Rate Deaths per 1000
    population 2) Crude Death Rate Deaths/Midyear
    Population 3) 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)

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?

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

Major State to State Migration Flows