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E-6. Population Estimates and Components of Change by County July 1, 2010–2014

December 2014

Contents

OFFICIAL STATE ESTIMATES  

This report presents preliminary state and county population estimates for July 1, 2014, revised estimates for July 1, 2010, July 1, 2011, July 1, 2012, and July 1, 2013, and components of population change.

Highlights

California’s population grew less than one percent between July 1, 2013 and July 1, 2014 to total 38.5 million persons. This represents an increase of 335,000 residents during the last fiscal year. The current percentage increase of 0.9 continues the moderate growth that California has experienced for the past several years.

Natural increase (births minus deaths) remains the primary source of the state’s growth. The natural increase of 243,000 is comprised of approximately 497,000 births minus 254,000 deaths. Births declined slightly from the previous fiscal year while deaths showed an increase. Net migration added 92,000 residents. Net migration includes all legal and unauthorized foreign immigrants, residents who left the state to live abroad, and the balance of hundreds of thousands of people moving to and from California from within the United States. The state gained about 151,000 net foreign immigrants last year.

Since the national census on April 1, 2010, the state has grown by 1,245,000 persons.

Methodology

The state and county population are independently estimated using population change models benchmarked on official decennial census counts. The state population is estimated using the Driver License Address Change method. County population proportions are estimated using the average of three separately estimated sets of proportions. The final distribution of proportions is applied to the independently estimated state control.

State Estimate. The state population is estimated using the Driver License Address Change (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, Medicare and Medi-Cal enrollment, immigration reports, 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.

County Estimates. Most of county populations estimates result from averaging the first three methods below. We use one of these methods: Housing Unit Method, Vital Statistics Method, or DLAC Method, in 13 counties with 65,000 populations or less.

DLAC Method. A modified version of the state Driver License Address Change (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 aid enrollments, 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, and housing units. 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.

Housing Unit Method (HUM). Vacancy rate data from the 2010 census is applied. 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 quarter’s population data.

Vital Statistics Method. County population estimates result from changes in county population values for births, deaths, and group quarters population.

Data Considerations

Sources. Data used in estimation models come from administrative records of 17 state and federal departments and agencies. Timeliness and coverage in these series vary. Corrections, adjustments or estimates may be made while preparing the estimates.

Accuracy. In general, estimates become less precise as the time from the last census increases. Data and models used to produce population estimates are subject to both measurement and nonmeasurement errors. This results in imperfect correlation between the data used to estimate the population and actual population change. The data and estimating models have been thoroughly tested with decennial census results that provide benchmarks for the estimates series. Data and methods are further refined and modified throughout the decade.

Acknowledgments

Phuong Nguyen produced the state and county estimates and prepared this report. Walter Schwarm produced the birth projections. Douglas Kuczynski and Alex Alvarado collected and prepared the group quarters data. Judi McClellan and Alex Alvarado produced the school enrollment projections. Douglas Kuczynski validated input data, formulas, and methodologies used in the current state and county estimates series

Suggested Citation

State of California, Department of Finance, Population Estimates and Components of Change by County, July 1, 2010-2014. Sacramento, California, December 2014.

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