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

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Presentation on theme: "Lane County 20-Year Coordinated Population Forecast Project Kick-off Public Meeting December 2, 2008 Population Forecasting Techniques Presentation by."— Presentation transcript:

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 Population Distribution, Lane County, 1990 and 2000 MalesFemales Population Age Schedules of Fertility, Mortality and Migration Determine the Age Structure of a 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, con’t.  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, con’t.  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  Doesn’t Fluctuate Greatly (unless new facility built or closed)

16 Average Annual Number of Housing Units Added

17 Housing Unit Method, con’t. PPH COBURG COTTAGE GROVE CRESWELL DUNES CITY EUGENE FLORENCE JUNCTION CITY LOWELL OAKRIDGE SPRINGFIELD2.54 VENETA WESTFIR UNINCORP LANE CO Occ. RateGQ COBURG95%0 COTTAGE GROVE95%152 CRESWELL95%58 DUNES CITY79%0 EUGENE95%6,078 FLORENCE85%56 JUNCTION CITY95%138 LOWELL92%0 OAKRIDGE88%0 SPRINGFIELD95%635 VENETA95%0 WESTFIR94%0 UNINCORP93%302 LANE CO94%7,418

18 Population Projection Techniques  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) Other Models/Techniques to Consider for All Areas in this Study

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/DAS–County 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 High: Assuming average annual increase rate from Medium: Assuming average annual increase rate from Low: Assuming average annual increase rate from (Ann. Time Series) Life Expectancy, Lane County, Estimates after 2005

23 Total Fertility Rate, Lane County, Mean age at births, Lane County,

24 Population Growth, Net Migration, Lane County, Population Net migrate rate ( per 1,000) 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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