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E-2. California County Population Estimates and Components of Change by Year — July 1, 2010–2015
- Press Release
- E-2. California County Population Estimates and Components of Change by Year — July 1, 2010–2015
OFFICIAL STATE ESTIMATES
This report presents preliminary state and county population estimates for July 1, 2015, revised estimates for July 1, 2010, July 1, 2011, July 1, 2012, July 1, 2013, July 1, 2014, and components of population change.
California’s population grew just under one percent between July 1, 2014 and July 1, 2015 to total 39.1 million persons. This represents an increase of 346,000 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 262,000 is comprised of approximately 507,000 births minus 245,000 deaths. Births and deaths increased from the previous fiscal year. Net migration added 84,000 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 145,000 net foreign immigrants last year.
Since the national census on April 1, 2010, the state has grown by 1,817,000 persons.
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 used to develop these estimates 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 a Vital Statistics Method in 16 counties with 72,000 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.
Vital Statistics Method. County population estimates result from changes in county population values for births, deaths, and group quarters population.
Sources. Data used in estimation models come from administrative records of numerous 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.
Phuong Nguyen produced the state and county estimates and prepared this report. Walter Schwarm produced the birth projections. Douglas Kuczynski 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.
State of California, Department of Finance, California County Population Estimates and Components of Change by Year, July 1, 2010-2015. Sacramento, California, December 2015.
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