The Intercensal Population Estimates and Projections Program

1. The Intercensal Population Estimates and Projections Program Signe I. Wetrogan Assistant Chief for Population Estimates and Projections Presented to Metropolitan Washington Council of Governments Washington, DC June 7, 2005

2. Intercensal Estimates Program • Required under Title 13, Section 181 - US Code • “During the intervals between each census of population…the Secretary, to the extent feasible, should annually produce and publish for each state, county, and local unit of general purpose government which has a population of 50,000 or more, current data on total population and population characteristics, and to the extent feasible, shall biennially produce and publish for other local units of general purpose government current data on total population.”

3. Population Estimates • National population estimates • Monthly by age, sex, race, and Hispanic origin • State population estimates • Annually by age, sex, race, and Hispanic origin • County population estimates • Annually by age, sex, race, and Hispanic origin • Functioning governmental units • Annually by total population for 39,000+ governmental entities • School Districts • Annually by total population

4. Housing Unit Estimates • State Estimates of Housing Units • Annually • County Estimates of Housing Units • Annually

5. Population Projections • National Projections • Current Interim projections – age, sex, selected race/Hispanic • Origin groups • Periodically prepared • State Projections • Current interim projections – age and sex • Periodically prepared

6. Uses of Population Estimates • Allocation of over $200 billion in federal funds • annually • Controls for federal surveys • Current Population Survey • American Community Survey • Denominators for statistical rates • Birth and death rates • Per capita income • Number of Senate clerk hires • Program planning • Location of public and private services

7. Methodology National, state, and county levels: Component method P2 = P1 + B - D + NM Subcounty level: Distributive housing unit method County population distributed to subcounty parts based on updated estimates of housing units

8. All Estimates Must Be Consistent County Pop. Total (Component Method) U.S. Pop. Total (Cohort-Component Method) Controlled To Controlled County Pop. Total State Pop. Total Totaled To Distributed To Sub-County Pop. Total (Distributive Housing Unit Method)

9. National Methodology National Methodology P2 = P1 + B - D + NM Beginning Population Census 2000 as enumerated Births and Deaths Registered births and deaths with demographic characteristics from National Center for Health Statistics (Receive micro records) P2 = P1 + B - D + NM Subcounty level: Distributive housing unit method County population distributed to subcounty parts based on updated estimates of housing units

10. National Methodology • International Migration • Net movement of the foreign-born population • Developed from annual change in foreign-born population as measured by the American Community Survey (ACS) • Net movement between the US and Puerto Rico • Measured by the Census 2000 • Emigration of native-born population • Measured by the Census 2000

11. State/County Methodology Administrative Records Component of population change method P2 = P1 + B - D + NM Done in cooperation with Federal State Cooperative Program for Population Estimates (FSCPE)

12. The Federal-State Cooperative Program for Population Estimates (FSCPE) In 1973 the Federal-State Cooperative Program for Population Estimates was formalized. The FSCPE was formed to: • Promote cooperation between states and the Census Bureau • Prepare a set of consistent county and subcounty estimates • Improve and advance estimates methodology • Enhance the recognition of local demographic work

13. The Federal-State Cooperative Program for Population Estimates (FSCPE) • District of Columbia contact: • Mr. Robert BeaslyData Services DivisionD.C. Office of Planning • Maryland contact: • Mr. Hal Sommers Vital Statistics AdministrationDept. of Health and Mental Hygiene • Virginia contact: • Dr. Julie Martin Cooper Center for Public ServiceUniversity of Virginia

14. State and County Component Method Births and deaths (NCHS, FSCPE ) Population (Census 2000) International Migration (ACS, Census 2000) Internal Migration (IRS) Internal Migration (SSA NUMIDENT) Medicare (CMS) Group Quarters Updates (FSCPE) State and County Estimating System Dissemination Products Monthly Survey Controls Denominators Media and Government Briefing Tables Analytical Tables

15. Estimates of County HH Pop Under 65 HHP=Household Population NI=Natural Increase NMIG=Net Domestic Migration NETMOVE=Net Movement from Abroad HHP2 = + NI + NMIG + NETMOVE - AGE HHP1 Persons Aging from age 64 to age 65 Net movement of Foreign-born population Last year’s estimate Emigration Tax return based rate FSCPE Net movement between US and Puerto Rico NCHS

16. Natural Increase • Births and Deaths • National Center for Health Statistics (NCHS) • Data provided by State FSCPE representative

17. Net Movement from Abroad • Distribution of total US estimates to states/counties • Distribute total US estimates of net movement of foreign-born • Use Census 2000 state/county distribution of foreign-born, noncitizens, who entered the US in the last 5 years • Distribute total US estimates of net movement to and from Puerto Rico • Use Census 2000 state/county distribution of population who entered the US from Puerto Rico in last 5 years • Distribute total US estimate of emigration of native-born population • Use Census 2000 distribution of population

18. Development of Net Migration for Population Under age 65 - Overview of Annual IRS File • Receive file in October of each year • Contents used in migration processing • Address, including ZIP code + 4 • Address as of when the return was filed • Number of exemptions by status • Number of dependents by status • SSN of filer and dependents • Name on tax return

19. Initial Processing of IRS Data Files • Match records from prior year file to current year file using filer’s modified SSN • Drop records that: • Do not match • Filer must have returns for two consecutive years • Have “deceased” in name field • Assume address on tax file is residence of tax filer and exemptions

20. Initial Processing • Geocode records to state/county • Use zipcode +4 to state/county coding guide • Compare geocodes for matched returns • If geocodes in time 1 and time 2 are different, the filer and exemptions on the return have migrated: • Have county of residence in year 1 • Have county of residence in year 2 • If geocodes in time 1 and time 2 are same, the filer and exemptions on the return are nonmigrants • Under age 65 exemptions are used

21. Calculate Net Migration Rate • Tabulate for each county: • Outmigrants • Number of under age 65 exemptions there in year 1 and in different county in year 2 • Inmigrants • Number of under age 65 exemptions there in year 2 and in different county in year 1 • Nonmigrants • Number of under age 65 exemptions there in year 1 and year 2

22. Calculate Net Migration Rate • Net migration rate = • In-migrants – out-migrants / • non-migrants + out-migrants

23. IRS Data Confidentiality • Title 26 – protects the confidentiality of IRS data • No individual record data can be released • Any publicly released data must go through suppression • SSNs are modified • Internal access to IRS is severely restricted

24. Develop Internal Migration Estimates for the Household Population • The net migration rate (derived from IRS data) is then applied to the household population under age 65 • This results in an estimate of net internal migration for the population under age 65 • Similar estimates are developed for the population over age 65 derived from Medicare data

25. Estimates of Group Quarters Population • Change in Group Quarters population is tracked through • an annual report prepared by the FSCPE • Additional data are collected from the DOD and the VA • This change is applied to the Census 2000 GQ count Types: Institutional Correctional Facilities Juvenile Facilities Nursing Homes Other Non- Institutional Colleges & Universities Military Quarters Other

26. State and County Component Method COUNTY TOTAL POPULATION = HHP0 <65 + HHP65+ + GQ • Control this population to the National estimate • Sum the controlled county population for each state • Distribute the controlled county population to the • subcounty level

27. Subcounty Distributive Housing Method Housing Units and Population (Census 2000) Building Permits (Census) BAS Data (Census) Vacancy/ PPH (Census 2000) Group Quarters Updates (FSCPE) Special Census Outputs County Population Estimates (State/County System) Subcounty Estimating System Dissemination Products HUD Funds Allocation MSA Designation Updates Media and Government Briefing Tables Analytical Tables

28. Place and County Subdivision Population Estimates Distributive Housing Unit Method • Change in Housing Units since the last Census at the subcounty level is used to distribute the estimated county population • Components of Housing Unit Change • Residential Construction • Mobile Home Placements • Housing Unit Loss • Subcounty Group Quarters data are taken from the same source as county Group Quarters data

29. Housing Unit Estimates Equation • HU2 = HU1 + (NC + NM) -HL • HU = Housing Units • NC = Estimated New Residential Construction • NM = Estimated New Residential Mobile Home Placements • HL = Estimated Residential Housing Loss

30. Estimated Residential Construction • Building permits • Compiled by the Census Bureau’s Manufacturing and Construction Division (MCD) • Nonpermitted construction • Estimated from Annual Survey of Construction and Census 2000 data

31. Mobile Home Placements • State mobile home shipment data distributed to subcounty areas based on the subcounty area’s share of state’s mobile homes • Mobile home data are no longer a 100% Census item

32. Housing Unit Loss • Based on data from 1997-2003 American Housing Survey (AHS) • 3 types of noninterviews: • Interior exposed to the elements • Demolished or disaster loss • House or mobile home moved • Housing unit loss rates developed based on: • Structure type • Age of structure

33. Subcounty Distributive Housing Unit Method • Subcounty Housing Units = Residential Construction + • Mobile Home Placements - Housing Unit Loss • Use each subcounty area’s HU based household population • estimate to distribute the county household population • Household population = (HU –vacants)* PPH • Vacants = Census 2000 rate • PPH = Census 2000 persons per occupied housing unit • Add the Group Quarters Population

34. Population Projections Methodology National and state -Component method P2 = P1 + B - D + NM Projections - not forecasts Outcomes of mathematical model Assume recent demographic trends continue

35. Further Information Population Estimates Web Site http://www.census.gov/popest/estimates.php Population Projections Web Site http://www.census.gov/population/www/projections/popproj.html Signe Wetrogan Assistant Chief for Population Estimates and Projections Signe.I.Wetrogan@census.gov (301) 763-2093