the intercensal population estimates and projections program

The Intercensal Population Estimates and Projections

Program

Signe I. WetroganAssistant Chief for Population

Estimates and Projections

Presented to Metropolitan Washington Council of Governments

Washington, DCJune 7, 2005

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.”

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

Housing Unit Estimates

• State Estimates of Housing Units–Annually

• County Estimates of Housing Units–Annually

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

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

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Methodology

National, state, and county levels:Component method

P2 = P1 + B - D + NM

Subcounty level:Distributive housing unit method

County population distributedto subcounty parts based onupdated estimates of housing units

U.S. Pop. Total(Cohort-Component Method)

State Pop. Total

County Pop. Total(Component Method)

Controlled To

Totaled To

Controlled County Pop. Total

All Estimates Must Be Consistent

Sub-County Pop. Total(Distributive Housing Unit Method)

Distributed To

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National Methodology

National Methodology P2 = P1 + B - D + NM

Beginning PopulationCensus 2000 as enumerated

Births and DeathsRegistered births and deaths withdemographic characteristics fromNational Center for Health Statistics(Receive micro records)

P2 = P1 + B - D + NM

Subcounty level:Distributive housing unit method

County population distributedto subcounty parts based onupdated estimates of housing units

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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

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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)

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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

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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

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State and County Component Method

Births anddeaths

(NCHS, FSCPE )

Population(Census

2000)

InternationalMigration

(ACS, Census

2000)

InternalMigration

(IRS)

InternalMigration

(SSANUMIDENT)

Medicare(CMS)

GroupQuartersUpdates(FSCPE)

State and County Estimating System

DisseminationProducts

Monthly Survey

ControlsDenominators

Media andGovernment

BriefingTables

AnalyticalTables

Estimates of County HH Pop Under 65

HHP=Household PopulationNI=Natural IncreaseNMIG=Net Domestic MigrationNETMOVE=Net Movement from Abroad

HHP2 =

FSCPE

NCHS

+ NI

Tax returnbased rate

+ NMIG

Net movement ofForeign-bornpopulation

Emigration

Net movement betweenUS and Puerto Rico

+ NETMOVEPersons

Aging from

age 64 to age 65

- AGE

Last year’s estimate

HHP1

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Natural Increase

Births and DeathsNational Center for Health Statistics (NCHS)

Data provided by State FSCPE representative

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Net Movement from Abroad

Distribution of total US estimates to states/countiesDistribute total US estimates of net movement of foreign-bornUse 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 RicoUse Census 2000 state/county distribution of population who entered the US from Puerto Rico in last 5 yearsDistribute total US estimate of emigration of native-born populationUse Census 2000 distribution of population

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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

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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 fieldAssume address on tax file is residence of tax filer and

exemptions

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Initial Processing Geocode records to state/county

– Use zipcode +4 to state/county coding guide

Compare geocodes for matched returnsIf 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

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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

InmigrantsNumber of under age 65 exemptions there in year 2 and

in different county in year 1

NonmigrantsNumber of under age 65 exemptions there in year 1 and

year 2

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Calculate Net Migration Rate

Net migration rate =In-migrants – out-migrants /non-migrants + out-migrants

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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

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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

Estimates of Group Quarters Population

Types: Institutional Correctional Facilities

Juvenile Facilities Nursing Homes Other Non- Institutional Colleges & Universities Military Quarters Other

• 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

COUNTY TOTAL POPULATION = HHP0 <65 + HHP65+ + GQ

State and County Component Method

• Control this population to the National estimate

• Sum the controlled county population for each state

• Distribute the controlled county population to the subcounty level

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Subcounty Distributive Housing Method

Housing Unitsand

Population(Census 2000)

BuildingPermits

(Census)

BASData

(Census)

Vacancy/PPH

(Census 2000)

Group QuartersUpdates(FSCPE)

SpecialCensusOutputs

County PopulationEstimates

(State/CountySystem)

Subcounty Estimating System

DisseminationProducts

HUDFunds

Allocation

MSADesignation

Updates

Media andGovernment

BriefingTables

AnalyticalTables

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

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Housing Unit Estimates Equation

HU2 = HU1 + (NC + NM) - HL

HU = Housing UnitsNC = Estimated New Residential ConstructionNM = Estimated New Residential Mobile Home Placements HL = Estimated Residential Housing Loss

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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

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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

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Housing Unit LossBased on data from 1997-2003 American Housing Survey (AHS)3 types of noninterviews:

Interior exposed to the elementsDemolished or disaster lossHouse or mobile home moved

Housing unit loss rates developed based on:Structure typeAge of structure

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Subcounty Housing Units = Residential Construction + Mobile Home Placements - Housing Unit Loss

Subcounty Distributive Housing Unit Method

• Use each subcounty area’s HU based household population estimate to distribute the county household population

Household population = (HU –vacants)* PPHVacants = Census 2000 ratePPH = Census 2000 persons per occupied housing unit

• Add the Group Quarters Population

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Population Projections Methodology

National and state -Component method

P2 = P1 + B - D + NM

Projections - not forecastsOutcomes of mathematical modelAssume recent demographic trends continue

Further Information

Population Estimates Web Sitehttp://www.census.gov/popest/estimates.php

Population Projections Web Sitehttp://www.census.gov/population/www/projections/popproj.html

Signe WetroganAssistant Chief for Population Estimates and ProjectionsSigne.I.Wetrogan@census.gov(301) 763-2093