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Population Estimates Process

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December 9 , 2024

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Huda Alkitkat, Ph. D.

Population Estimates Program Manager

Population Research Center

College of Urban and Public Affairs

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Background

Oregon Population Estimates Program

  • As mandated by Oregon law (ORS 190.510 to 190.620), the Population Research Center at Portland State University produces annual certified population estimates for the state, its counties, and its cities.

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  • These estimates help decision-makers and planners in many sectors: health, education, infrastructure, and housing, and they are used to distribute the State's revenues.

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Background

Oregon Population Estimates Program

  • Population estimates are prepared as of July 1 of each year.
  • Preliminary estimates are released on November 15th each year
  • Certified estimates are published on December 15th each year
  • Supplemental reports are prepared and published quarterly to reflect changes in population due to annexations
  • All residents of Oregon’s cities, counties, and unincorporated areas are included in the population estimates.

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Administrative Data

Oregon Population Estimates Program

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  • Birth and death (Oregon Health Authority)
  • School enrollment (Oregon Department of Education)
  • Employment (Oregon Employment Department)
  • Issued driver licenses (Oregon Department of Transportation)
  • State income tax exemptions (Oregon Department of Revenue)
  • Federal income tax exemptions (internal Revenue Service (IRS)
  • Medicare enrollment data (The Centers for Medicare & Medicaid Services (CMS)

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Survey Data

Oregon Population Estimates Program

  • Request annual information from all counties and cities
  • Information includes annual changes in the housing units, number of mobile homes, inventory of special housing units (campers, RVs, tents, boats, cars, … places used for permanent living)., and data on the group quarters and people living there.

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Annual Housing Unit & Population Survey (cities & counties)

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Oregon Population Estimates Program

  • Section A: Housing Units

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    • Added : New construction / Converted

    • Lost: demolitions – or conversions to non-residential use

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Annual Housing Unit & Population Survey (cities & counties)

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Oregon Population Estimates Program

  • Section B: Inventory of Mobile Homes
    • The number of mobile homes (In-Out)and the number of persons living in these homes, if available.
  • Section C: Inventory of Special Housing Units
    • Campers/RVs, tents, boats, cars, and other places used for permanent living and the number of persons living in these homes, if available.
  • Section D: Group Quarters
    • Places where people live or stay in a group living arrangement, which are owned or managed by an entity or organization providing housing and/or services for the residents.

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Annexations

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Oregon Population Estimates Program

  • Monitoring city annexations throughout the year
    • Notification about annexations from the office of the Secretary of State.
  • Annexation survey:
    • Housing units (Single-Multifamily units).. Vacant/Occupied
    • Mobile homes
    • GQs
  • Annexed population is added to the previously certified population (Quarterly reports)

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Methods

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Oregon Population Estimates Program

  • State population estimates:
    • The cohort component method (CCM)

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  • County population estimates:
    • Ensemble method (CCM + Ratio correlation ( RC))

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  • City/Unincorporated population estimates:
    • Housing unit method

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Population this year = Population last year + Births - Deaths + In-migrants - Out-migrants

household population is correlated with social, economic, and health indicators; therefore we can track changes in those data to impute population growth or decline

Change in population is related to change in the number of housing units, average household size, and vacancy (for households) and the GQ population

State population estimate

County population estimates

City/Unincorporated population estimate

Controlled to

Controlled to

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Population from the 2020 Census to the current year

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Net Housing Unit Change & Net GQ Population Change between 2020 Census date (April 1st 2020) and June 30, 2020

Average Household Size and Vacancy Rate

July 1, 2020 Population estimates

Net Housing Unit Change & Net GQ Population Change between July 1st , 2020 and June 30, 2021

Average Household Size and Vacancy Rate

July 1, 2021 Population estimates

Net Housing Unit Change & Net GQ Population Change between July 1st , 2021 and June 30, 2022

Average Household Size and Vacancy Rate

July 1, 2022 Population estimates

Net Housing Unit Change & Net GQ Population Change between July 1st , 2022 and June 30, 2023

Average Household Size and Vacancy Rate

July 1, 2023 Population estimates

Net Housing Unit Change & Net GQ Population Change between July 1st , 2023 and June 30, 2024

Average Household Size and Vacancy Rate

July 1, 2024 Population estimates

Hermiston, OR (EXAMPLE–NOT REAL DATA)*

4/1/2020 (Census)

7/1/2020

7/1/2021

7/1/2022

7/1/2023

Starting Population

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19,354

19,503

19,633

19,969

Initial Vacancy Rate

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4.4%

4.2%

4.3%

4.3%

Initial Average Household Size

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2.86

2.89

2.88

2.88

Net Housing Unit Change

-

+65

+92

+116

+100

Net Group Quarters Population Change

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0

5

15

0

Final Housing Units

6,962

7,027

7,119

7,235

7,335

Preliminary New Population

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19,213

19,710

19,941

20,216

County Control Adjustment

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(29)

(401)

(311)

(233)

Final Group Quarters Population

319

319

324

339

339

Final Vacancy Rate

4.4%

4.2%

4.3%

4.3%

4.2%

Final Average Household Size

2.86

2.89

2.88

2.88

2.89

Final Population

19,354

19,503

19,633

19,969

20,322

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Oregon Population Estimates Program

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Example for a County, County balance and cities inside the County from 2020 Census to the current year

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Oregon Population Estimates Program

  • Why might the average number of persons per household (PPH) be going down
    • Aging in place
    • Fewer children
    • Children moving out of parents’
    • Doubled up moving out

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  • Why might the vacancy rate be going up
    • COVID-19 pandemic
    • More vacation rentals
    • More part-time rentals

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Why Do we revise population estimates

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Oregon Population Estimates Program

  • With each new release of the annual estimates, to produce the most accurate certified population estimate for the current year, the entire time series of estimates is revised for all years back to the beginning of the decade to reflect the increased availability of data ( IRS data (2 years after the year it describes)- Vacancy /PPH( ACS comes 1 year after the year it describes).

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These revisions increase the accuracy of net changes since the census benchmark (2020 Census).Specifically for the COVID-19 period /wildfires period.

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  • Based on a request from the city ( The city provides updated information back to the begging of the decade)

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  • City collaborate with the PRC/PSU to conduct a local survey.

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Why Do we revise population estimates

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Oregon Population Estimates Program

  • For each year, on December 15, the revised figures are the most accurate for previous years and the certified figures are the most accurate for the current year.

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  • When we revise the estimates for previous years, we keep the certified estimates figures for those previous years as they are. Please do not link the revised estimates for previous years to the annual certified estimates published annually for the last years based on the most accurate data available at that time.

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Population Estimates Timeline

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Oregon Population Estimates Program

May/June

July

November 15th

December 15th

April 15th

Update

( Contact persons)

Annual Housing Unit and Population Survey (AHUPS)

Preliminary estimates

Certified estimates

Annual report

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Preliminary population estimates- Certified population estimates

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Oregon Population Estimates Program

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  • The preliminary population estimates released by mid of November
  • The preliminary population estimates are subject to revision before certification on December 15th
  • All questions/comments/petitions should be directed to the Population Estimates Program at popest@pdx.edu
  • First review period: Between November 15th and December 15th

(If differences regarding the estimate are not resolved during the first review period, the PRC/PSU will certify the preliminary estimate on December 15th of the estimate year.

  • Second review period: Between December 15th and March 31�This period is to allow cities to assemble and present data to the PRC/PSU that could not be assembled during the initial review period. If differences between the city and the PRC/PSU are resolved during the second review period the PRC/PSU will issue a revised certificate of population for the city retroactive to December 31st of the estimate year.

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For Comments & Questions

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Email: popest@pdx.edu

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