Department of Finance
915 L Street
Sacramento, CA 95814

E-4 Population Estimates for Cities, Counties and the State, 2001–2009,  Benchmark

May 2009

Acknowledgements

Daniel Sheya prepared this report. Daniel Sheya prepared the city estimates, Linda Gage prepared the state and county estimates, Doug Kuczynski and Walter Schwarm provided analytical expertise in city estimates while producing military, group quarters, household population and housing estimates. Evaon Schnagl provided analytical expertise for city, county, and state estimates. Mary Heim, Chief of the Demographic Research Unit and John Malson, Assistant Chief of the Demographic Research Unit provided general direction.

Suggested Citation

State of California, Department of Finance, E-4 Population Estimates for Cities, Counties and the State, 2001–2009, with 2000 Benchmark. Sacramento, California, May 2009.

• E-4 Population Estimates for Cities, Counties and the State, 2001–2009, with 2000 Benchmark (.xls, <1 MB)

Contents

This report provides population estimates for January 1, 2001 through January 1, 2008 and provisional population estimates for January 1, 2009 for the state, counties and cities. The population estimates benchmark for April 1, 2000 is also provided.

Methodology

Introduction. The January state, county, and city populations are independently estimated using change models benchmarked to base year 2000 that corrects for census omissions and geocoding errors. The state population estimate is produced using the Driver License Address Change (DLAC) method. County population proportions result from the average of three separately estimated sets of proportions, as described below. The final distribution of county proportions is applied to the independently estimated state total to derive the county estimates. The city estimates, produced using the Housing Unit Method (HUM) detailed below, 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 estimates 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 conversions from the 2000 benchmark or a prior year’s estimate. Housing unit changes are supplied by local jurisdictions and the U.S. Census Bureau. Of the 537 reporting jurisdictions, all 537 provided data this year. Occupied housing units (households) are estimated by applying a derived civilian vacancy rate, based on 2000 benchmark data, to the estimated civilian housing units. Adjustments to the census occupancy rates (occupied units/total units) are occasionally made, however, foreclosures and other housing market indicators were not used to adjust vacancy rates. Occupied military units are added to civilian occupied units to calculate total households. Military surveys are used to track military changes, including base realignments and closures. The household population estimate is derived by multiplying the number of households by the current persons per household. The persons per household estimates are based on 2000 benchmark data and are updated by incorporating the current county population series into these estimates. Persons per household can be further changed when a jurisdiction adds large numbers of special types of housing, such as adult living. The benchmark group quarters population is updated using the reported population change in group quarters facilities. 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 proportions result from averaging three methods.

Driver License Address Change Method. A modified version of the state DLAC method is used for counties. County proportions of the state total result from changes in county population values for births, deaths, school enrollment, foreign and domestic migration, medical care data for the population over 65, and group quarters population.

Ratio-Correlation Method. This method models change in household population as a function of changes in the distributions of driver licenses, school enrollments, housing units, and deaths. Estimates of county group quarters are added.

Tax Return Method. County proportions are derived by the U.S. Census Bureau using matched federal income tax returns to estimate inter-county migration along with vital statistics, group quarters, and other information for the population aged 65 and over.

State Estimate. The state population is estimated using the DLAC method. This composite 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, tax return data, medical care data for the population over 65, immigration, elementary school enrollments, and group quarters population are among the data used in this method. All data are in summary tables and do not reveal the identity of any individual.

Data Considerations

Sources. Data used in estimation models come from administrative records of several state and federal government departments and agencies, as well as numerous local jurisdictions. Since timeliness and coverage in these series vary, corrections, smoothing, and other adjustments may be applied.

Accuracy. Data and models used to produce population estimates are subject to measurement and non-measurement errors. The data and estimating models were thoroughly tested with decennial census results that provide benchmarks for the estimates series. The total state estimate was within one-half of one percent (0.5%) of the 2000 census count; county estimates varied by an average of 1.9 percent, and city estimates by an average of 5.6 percent. Data and methods are further refined and modified throughout the decade.

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