OFFICIAL STATE ESTIMATES
This updated report presents revised state and county population estimates benchmarked to the2000 and 2010 decennial census data. The statistical "error of closure" procedure corrects the estimation error in the original estimates. These estimates supersede those in the Department of Finance E-6 series for the 2000s published in August 2011.
The state and county populations 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. County population proportions result from
averaging three methods.
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, 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.
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.
State of California, Department of Finance, Revised County Population Estimates and Components of Change by County, July 1, 2000-2010. Sacramento, California, December 2011.