E-4 Population Estimates for Cities, Counties, and the State, 2001-2010, with 2000 & 2010 Census Counts

Version History

  • 1.3  (Revised 11/9/2012)
  • 1.2  (Revised 10/12/2012)
  • 1.1  (Revised 9/14/2011)


This report provides revised population estimates for the state, counties, and cities for January 1, 2001 through January 1, 2010.  It also includes 2000 and 2010 decennial census counts.  The revised estimates attempt to provide a consistent data series reflecting both decennial census counts by utilizing the Error of Closure (EOC) adjustment procedure.

Error of Closure Methodology

These revised intercensal estimates for 2001-2010 for the state, county, and city population are produced by modifying previous estimates produced for the 2001-2010 decade to account for differences between the Demographic Research Unit (DRU) test estimate on 4/1/2010 and enumerated census counts of the same day. The procedure to close these differences is called the “Error of Closure,” or EOC. The concept is to preserve the original growth patterns that transpire in the annual DRU estimates for population, but to realign the ten year growth patterns with the bookend census data.

The EOC adjustment is applied after two consecutive censuses have been conducted; for this report, the two censuses are for 2000 and 2010. The EOC adjustment revises previously calculated intercensal estimates to mitigate the effects of estimation errors in a data series over the decade coupled with differential accuracy of two decennial censuses. For this report, the final adjustment was made after the 2010 census data became available. This procedure statistically distributes the difference, called the error, between the 2010 census counts and the DRU test estimate calculated as of the census date – April 1, 2010 – to the previously calculated annual 2001 to 2010 estimates.

Sub-county total population estimates have been controlled to the county EOC estimates, and the county EOC estimates were controlled to the state EOC estimates.

Further discussion of the EOC technique and estimation procedures may be found in Appendix A.

Information and methodology about annual city, county, and state estimates produced by DRU may be found in E-1 City, County, and the State Population Estimates with Annual Percent Change.

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. This report contains Count Question Resolution (CQR) corrections through September 20, 2012.  The E-4 report will be updated with CQR corrections when they are reported and approved by the U.S. Census Bureau.


Walter Schwarm prepared this report. Daniel Sheya prepared the city estimates, Linda Gage prepared the state and county estimates, Doug Kuczynski provided analytical expertise while producing military, group quarters and city estimates. Walter Schwarm provided analytical and procedural expertise in city estimates. 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, 2001-2010, with 2000 & 2010 Census Counts. Sacramento, California, November 2012.