Lane County 20-Year Coordinated Population Forecast Project Kick-off Public Meeting December 2, 2008 - PowerPoint PPT Presentation

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Lane County 20-Year Coordinated Population Forecast Project Kick-off Public Meeting December 2, 2008

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Lane County 20-Year Coordinated Population Forecast Project Kick-off Public Meeting December 2, 2008 Population Forecasting Techniques Presentation by – PowerPoint PPT presentation

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Title: Lane County 20-Year Coordinated Population Forecast Project Kick-off Public Meeting December 2, 2008


1
Lane County 20-Year Coordinated Population
Forecast Project Kick-off Public Meeting December
2, 2008
  • Population Forecasting Techniques
  • Presentation by
  • Population Research Center
  • Project Team

2
Population Research Center Project Team
  • Risa Proehl, Project Lead
  • Danan Gu, Demographic Analyst
  • Ken Radin, GIS Analyst
  • George C. Hough Jr., Director

3
Population Forecasts Process
  • Develop Demographic Models Using Historic and
    Recent Data
  • Analyze Past and Recent Population Trends -
    Reasons for Change, Continuous or Short-term?
  • Gather Information About Recent and Planned
    Future Housing and Population change (housing
    developments, construction of new GQ facilities,
    new employers)
  • Make Assumptions About Future Housing and
    Population Change
  • Revise Forecasts on a Regular Basis

4
Outline
  • Population Trends Lane County
  • Population Projection Methods
  • Assumptions About the Future

5
Population Change in Lane County
  • Lane County Grew Consistently 1900 to 2008
  • Lane County Grew in Absolute and Relative
    Reflecting Societal/Economic Conditions
  • Lane County Population Change Has Shifted from
    High Growth Scenario of 3 per year to about 1
    per annum
  • The Eugene and Springfield Shares of County
    Population Increased but Have Become More Stable
    in Recent Years

6
Lane County Grew Consistently Over the Past
Century
7
Population Change 1900 to 2008 Reflects Decade
Economic Changes Higher Growth and Lower Growth
Periods
8
City Population Shares Have Stabilized Over
Recent Times
9
Population Projection Techniques Primary Models
for this Study
  • COHORT-COMPONENT METHOD
  • for Lane County, Eugene, Springfield
  • Relies on Age-Sex Schedules of Demographic
    Behavior
  • Population Pyramid Displays Age Structure
  • Mortality Fairly Constant over Time
  • Fertility Decreased Teen Fertility, Older
    Mothers and Latino Births
  • Migration In Lane Co., Mostly Influenced by
    Common College Pattern and Employment
    Availability
  • Migration Rates Subject to Greater Fluctuation
    than Mortality and Fertility and more
    unpredictable
  • Three Scenarios of Growth High, Medium, Low

10
Age Schedules of Fertility, Mortality and
Migration Determine the Age Structure of a
Population
Males
Females
Population Distribution, Lane County, 1990 and
2000
Population
11
Mortality Age Schedules Are Similar for 1990 and
2000
12
Fertility Schedules Are Similar for 1990 and 2000
13
Migration Schedules Show Dominance of College
Migration
14
Population Projection Techniques Primary Models
for this Study, cont.
  • HOUSING UNIT METHOD
  • for Ten Smaller Cities, Unincorporated Area, Area
    Outside UGBs
  • Housing Unit Growth Trend Actual, Trend County
    Shares
  • Housing Unit Type (single-/multi-family)
  • Household Composition Persons
  • Persons Per Household
  • Occupancy Rates
  • Add Group Quarters Population
  • Based on Medium Growth Scenario one scenario as
    smaller areas have more variability than larger
    areas
  • Controlled to Cohort-Component Model Results for
    County

15
Housing Unit Method, cont.
  • Fluctuations in housing unit growth follows
    economic trends with Exceptions
  • PPH
  • Factors that influence PPH Race/Ethnicity, Age
    (fertility), Economy
  • Generally Decreasing in U.S.
  • Occupancy Rates - Seasonal Housing
  • Ranges from 79 to 95
  • Group Quarters Population Ranges from 0 to 5 of
    Total Population
  • Doesnt Fluctuate Greatly (unless new facility
    built or closed)

16
Average Annual Number of Housing Units Added
17
Housing Unit Method, cont.
PPH 1990 2000 2007
COBURG 2.41 2.64  
COTTAGE GROVE 2.60 2.54  
CRESWELL 2.68 2.76  
DUNES CITY 2.30 2.23  
EUGENE 2.30 2.27 2.25
FLORENCE 2.21 2.02  
JUNCTION CITY 2.42 2.55  
LOWELL 2.90 2.72  
OAKRIDGE 2.45 2.35  
SPRINGFIELD 2.54 2.54  
VENETA 2.79 2.85  
WESTFIR 2.84 2.76  
UNINCORP 2.69 2.58  
LANE CO 2.49 2.42 2.41
2000 Occ. Rate GQ
COBURG 95 0
COTTAGE GROVE 95 152
CRESWELL 95 58
DUNES CITY 79 0
EUGENE 95 6,078
FLORENCE 85 56
JUNCTION CITY 95 138
LOWELL 92 0
OAKRIDGE 88 0
SPRINGFIELD 95 635
VENETA 95 0
WESTFIR 94 0
UNINCORP 93 302
LANE CO 94 7,418
18
Population Projection Techniques
Other Models/Techniques to Consider for All Areas
in this Study
  • For Comparison and to Serve as a Check
  • Shift-Share and Other Ratio Methods
  • Trend Extrapolation
  • Simple Economic/Employment Model
  • Land Use and Capacity
  • Additional Housing Unit Models (in addition to CC
    models)

19
Data
  • Background Information
  • Some Entered Directly into Projection Models
  • Some Provide Support for Assumptions Made for
    Future Change
  • All Data Available for Lane County, Many
    Available for Individual Cities (Census, Land
    Use, Housing, Births, Group Quarters Population)

20
Data
  • Data Sources
  • 1990 and 2000 Census Data
  • ACS Data post-2000
  • Vital Statistics
  • Building Permit Data
  • Annual Housing and Population Data from Local
    Jurisdictions
  • PRC Annual Population Estimates, post-2000
    Revised to Current Boundaries and UGBs
  • School Enrollment Data
  • Land Use Data and Plans for Future Development
  • Local Studies e.g., School Enrollment
    Projections, Previous Coordinated Plans, TSP
  • Employment and Labor Force Data and Projections
  • Previous OEA/DASCounty Projections to 2040
  • Confer with OEA about Current and Revised
    Forecast
  • Information from local Government Staff, Public
    Meetings

21
Future Conditions and Considerations
  • Assumptions are Based on Past and Recent Trends,
    Occurrence of Events, and Plans for Future
    Housing
  • Future Assumptions for Lane County?
  • Mortality Slight Increase in Longevity
  • Fertility Slightly Older Mothers and Latino
    Births
  • Migration Employment and Group Quarters
    Populations
  • Assumptions about PPH, Vacancy Rates, Housing
    Construction
  • Some Current Conditions are Assumed to be the
    Same in Future (e.g. land use zoning, residential
    densities, UGBs expand as needed)
  • Citizen and Governmental Input Combined with
    Demographic Expertise Will Produce the Most
    Reasonable or Likely Forecasts

22
Life Expectancy, Lane County, 1970-2035
Estimates after 2005

High Assuming average annual increase rate from
1970-2005. Medium Assuming average annual
increase rate from 1990-2005. Low Assuming
average annual increase rate from 2000-2005.
(Ann. Time Series)
23
Total Fertility Rate, Lane County, 1990-2035
Mean age at births, Lane County,1970-2035
24
Population Growth, Net Migration, Lane County,
1980-2005
Net migrate rate ( per 1,000)
Population
Year
25
Projections and Forecasts General Comments
  • Projections Are More Accurate in Short-Term
  • The Larger the Geographic Area, The More Accurate
    the Projection
  • Population Forecast is a Tool to Help with
    Planning and Serves as a Guide not a Guarantee
    of What Will Occur
  • Revisions to Forecasts Should be Made Regularly!
  • PRC Utilizes Best Practices Professional
    Associations
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