population estimates |
Methodology for Subcounty Total Resident Population Estimates for (Vintage 2007):
|
HU07 | = Estimated 2007 housing units |
HU00 | = Census 2000 housing units retabulated to current geography |
NC07 | = Estimated residential construction, April 1, 2000 to July 1, 2007 |
NM07 | = Estimated new residential mobile home placements, April 1, 2000 to July 1, 2007 |
HL07 | = Estimated residential housing loss, April 1, 2000 to July 1, 2007 |
1A. Census 2000 Housing Units (HU00) –-Census 2000 housing units at the subcounty level reflect boundary updates that are legally effective as of January 1, 2007. The housing unit counts also include Count Question Resolution (CQR) actions, and geographic program revisions benchmarked in the Master Address File (MAF)/TIGER Database through May of 2007.
1B. Estimated Residential Construction (NC07) –-New residential construction is calculated using the following formula:
NC07 = (BP07 * 0.98) + NPC07
Where:
NC07 | = Estimate of new residential construction for the period: April 1, 2000 to July 1, 2007 |
BP07 | = The residential building permits that result in the construction of new units for the period April 1, 2000 to July 1, 2007 include permits issued in calendar years 2000-2006 (allowing for a six-month lag time between permit issuance and completed construction). |
NPC07 | = Estimate of new residential construction in non-permit issuing areas for the period: April 1, 2000 to July 1, 2007 |
Note: We assume that using ¼ of the residential construction input data for the year 2000 represents the three-month period from April 1, 2000 to July 1, 2000.
Building permit data are compiled from internal data files developed by the Census Bureau’s Manufacturing and Construction Division (MCD). These files include imputed permits where a jurisdiction did not report permit issuance for the entire year.
Two percent of all building permits never result in the actual construction of a housing unit (as derived from U.S. Census statistics on housing starts and completions; available on the Census Bureau website at http://www.census.gov/const/www/newresconstindex.html ).The annual Survey of Construction (SOC) produces regional estimates of housing units constructed in non-permit issuing jurisdictions. The regional SOC estimates are then distributed to all subcounty areas where MCD lacks building permits for the estimates period. This distribution is based on the subcounty area’s share of the regional total of units in nonpermit-issuing jurisdictions as of Census 2000.
We receive monthly reports on mobile home shipments from MCD. These monthly reports are summed to calculate the annual total of state mobile home shipments.
To allocate the state mobile home shipment data to subcounty areas, we apply the subcounty area’s share of state mobile homes as of Census 2000 to the updated number of state mobile home shipments. The type of structure question indicating that a housing unit is a mobile home was on the sample questionnaire in Census 2000. The following steps describe the process we use to produce sample data consistent with the 100-percent housing unit data in current geography:1D. Estimated Housing Loss (HL07) –- Housing unit loss is calculated by applying an annual rate of loss to the previous year’s housing unit estimate. The 2007 estimates of housing unit loss are based on data derived from the 1997-2003 American Housing Survey (AHS) national sample. The following three types of AHS housing situations are considered to represent permanent loss of a housing unit.
Type B, 16 -- Interior exposed to the elements
Type C, 30 –- Demolished or disaster loss
Type C, 31 –- House or Mobile Home moved
Annual housing unit loss rates based on these types of housing loss were then developed for housing units based on structure type and age of structure. Type C, 31 houses were excluded before the final rate was computed. The rates for the categories are as follows:
Category |
Rate |
---|---|
House, Apartment, or Flat built in: | |
1990-1997: |
0.031 percent |
1980-1989: |
0.054 percent |
1970-1979: |
0.103 percent |
1960-1969: |
0.172 percent |
1950-1959: |
0.249 percent |
1940-1949: |
0.324 percent |
Pre-1940: |
0.364 percent |
Mobile Homes: | 1.58 percent |
Other: | 0.19 percent |
Overall loss rate: | 0.295 percent |
The type and age of housing units in Census 2000 for each governmental unit are used to estimate its housing unit loss. Other housing includes a variety of situations not defined above, including boats, recreational vehicles, or other housing arrangements.
1E. Estimates Review –The housing unit estimates are distributed to members of the Federal State Cooperative Program for Population Estimates (FSCPE) for review. Some FSCPE members provide revisions to the preliminary estimates of housing units based on information they compile from the jurisdictions within their respective states. Submitted revisions to the housing unit estimates are reviewed and often result in changes to the final housing unit estimates.
Step 2. Producing an Uncontrolled Subcounty Household Population Estimate
The uncontrolled subcounty household population estimate follows this equation:
UCHHP07 = HU07 * OCC00 * PPH00
Where:
UCHHP07 | = Uncontrolled subcounty household population estimate for 2007 |
HU07 | = July 1, 2007 housing unit estimate |
OCC00 | = Census 2000 occupancy rate |
PPH00 | = Census 2000 persons per household |
Step 3. Producing a Controlled Subcounty Household Population Estimate
The final step in producing a household population estimate is to control the uncontrolled subcounty estimates to the published county totals. The following equation describes the calculation of a controlled household estimate:
SCHHEST07 = UCHHP07*(CHP07/SUCHHP07)
Where:
SCHHEST07 | = 2007 subcounty household population estimate |
UCHHP07 | = Uncontrolled household population estimate for 2007 |
CHP07 | = County 2007 household population estimate |
SUCHHP07 | = County sum of UCHHP07 for all subcounty areas |
Step 4 . Group Quarters Population Estimate
The group quarters component of the total estimate is primarily a combination of military personnel living in barracks, college students living in dormitories, and persons residing in other types of institutions. Inmates of correctional facilities and persons in health care facilities also are included in group quarters.
We use group-quarters population data from two sources to estimate subcounty populations: (1) Census 2000 counts of group-quarters population by facility type for each subcounty area, and (2) a time series of individual group-quarters records from the Group Quarters Report (GQR). State representatives of the Federal State Cooperative Program for Population Estimates (FSCPE) prepare the GQR.
These two sets of group-quarters population data are used to derive a time series of group-quarters population through the following process:
Part 1. We sum the facility-level group quarters populations from the GQR to the subcounty level by the seven facility types for each estimate date in the time series. Then, we calculate the year-to-year change indicated by the aggregated GQR time series of population.
Part 2. We aggregate the group quarters population from Census 2000 to the subcounty level by the seven facility types. Then, we apply the time series of numeric year-to-year change to the Census 2000 data to create a census-based time series of group quarters population at the subcounty level for each of the seven facility types.
Step 5 . Final Subcounty Population Estimate
To produce the final subcounty population estimate, the controlled household population estimate and the group quarters population estimate are added together.
SCEST07 = SCHHEST07 + GQ07
SCEST07 | = Final 2007 subcounty population estimate |
SCHHEST07 | = 2007 subcounty household population estimate |
GQ07 | = 2007 subcounty group quarters population estimate |
Step 6 . Estimates Review
Before public dissemination, the subcounty population estimates are distributed to FSCPE members for review. Some FSCPE members provide revisions to the preliminary estimates of population based on their own analysis.
1 Includes the following statistical equivalents: parishes (Louisiana), boroughs and Census Areas (Alaska).
2 Primitive geography describes a partition of the country into the lowest level of mutually exclusive entities that can be aggregated to all higher levels of geography for which the Census Bureau produces estimates.