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E-1 Population Estimates for Cities, Counties, and the State January 1, 2012 and 2013

May 2013

Contents

This report provides revised population estimates as of January 1, 2012 and provisional population estimates as of January 1, 2013 for the state, counties, and cities and includes a calculation of annual percent change. These population estimates incorporate 2010 census counts.

Methodology

Introduction. Estimates for the January state, county, and city populations are independently calculated using change models benchmarked to federal census counts included in the 2010 Summary  File 1. The state population estimate is an average of four separate methods: State Driver License Address Change (DLAC) Method, County DLAC Method, Housing Unit Method (HUM), and an Administrative Records (ADREC)   Method developed by the U.S. Census Bureau.

County population estimates utilize four separate methods, including three methods also used for state population estimates and a ratio correlation method. Each of these methods is described below. Final county population estimates are adjusted to the independently calculated state total. City estimates are produced using the HUM detailed below, and are raked to be consistent with the state and county estimates. Through the raking process, city and unincorporated area estimates are aligned with the more robust state and county estimating models that employ multiple data sets available only at the higher geographic levels.

City and Unincorporated Area Estimates. The HUM is used to   estimate total and occupied housing units, household size, household population, and group quarters population. Housing units are estimated by adding new construction and annexations and subtracting demolitions, and adjusting for units lost or gained by conversions. Annual housing unit change data are supplied by local jurisdictions and the U.S. Census Bureau. Occupied housing units are estimated by applying a derived civilian vacancy rate, based on 2010 benchmark data, to the estimated civilian housing units. Adjustments to census vacancy rates are made periodically. Exact data on foreclosures or other housing market indicatorsare not available to adjust vacancy rates.  Military occupied housing units are added to civilian occupied housing units to calculate total occupied housing units. Military surveys are used to track military changes including base realignments and closures. Household population estimates are derived by multiplying the number of occupied housing units by the current persons per household. The persons per household estimates are based on 2010 census benchmark data and are adjusted by raking the current county population series into these estimates. The group quarters population is based on the Census Bureau’s 2010 SF1 File counts on group quarters and annually adjusted  using reported changes for group quarters by state, federal, and local agencies. The household and group quarters populations are summed to produce the initial city population estimates. These estimates are aligned to the county estimates described below.

County Estimates. County population estimates are developed using four separate methods. Some methods in some counties are in a research and evaluation phase and are only being used for evaluation at this time.

County Driver License Address Change (DLAC) Method. A modified version of the state DLAC method is used for counties. County-level estimated population results from changes in annual counts for births, deaths, school enrollment, foreign and domestic migration, medical care enrollment data for the population 65 and over, and group quarters population.

Housing Unit Method (HUM). Vacancy rate data from the 2011 1-year ACS is applied where it is available (1-year data are available for 40 counties). The vacancy rates provided by Census 2010 are applied for counties that lack updated vacancy data from the 2011 1-year ACS. Assuming the average number of persons in households remains unchanged from Census 2010, county populations are then calculated from estimated counts for the household and group quarters population data.

Ratio-Correlation Method. This method models change in household population as a function of changes in the distributions of births, deaths, driver licenses, public elementary school enrollment, labor force, and county housing unit counts. Estimates of county group quarters are added.

Administrative Records (ADREC) Method. County population estimates are derived using the U.S. Census Bureau ADREC Method, which are updated from their most recent estimates series and the Demographic Research Unit’s (DRU) own estimated half-year migration data along with the most recent vital statistics (from the California Department of Public Health) and group quarters data obtained from several state and local sources. The DRU’s half-year migration data are calculated using the percentage of change in net migration in two consecutive years.

State Estimate. The state population is estimated from averaging four methods.

State Driver License Address Change (DLAC) Method. This component method separately estimates the population under age 18, 18 through 64, and 65 years and older. Administrative records such as births, deaths, driver license address changes, legal migration to the United States, medical care enrollment data for the population 65 and over, immigration, public elementary school enrollments, and group quarters population are the data used in this method. All data are in summary tables and do not reveal the identity of any individual.

Administrative Records (ADREC) Method. State January population estimates are derived by using the ADREC estimated migration data on the percentage of change in net migration in two consecutive years along with vital statistics and group quarters data.

Housing Unit Method (HUM). The small area estimates produced with the HUM are summed to the county and the counties are summed to produce a state estimate.

County Driver License Address Change (DLAC) Method. The modified DLAC Method used in county estimates is compiled and summed to produce the fourth state estimate.

Data Considerations

Sources. Data used in estimation models come from administrative records of several state and federal government departments and agencies, and from the local jurisdictions for which Finance produces population estimates. Because timeliness and coverage in these series vary, corrections, smoothing, and other adjustments may be applied. Changes to 2010 Summary File 1 data in the classification of student housing on or near campus was necessary to remain consistent with the census group quarters definition. In only a few instances, some student housing (residence hall and apartment units) counted as household population in the census was redefined as group quarters student housing population. College dorm group quarters population is defined as student population living in residence halls and apartment units located on or near college campuses.

Suggested Citation

State of California, Department of Finance, E-1 Population Estimates for Cities, Counties and the State with Annual Percent Change — January 1, 2012 and 2013. Sacramento, California, May 2013.

Contact Information

For questions on the E-1, contact Doug Kuczynski or Alex Alvarado in the Demographic Research Unit at 916-323-4086 or e-mail at ficalpop@dof.ca.gov.

 

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