Calculating Sub-county Area Labor Force Data for Historical Time Periods

Introduction

Labor force data for sub-county areas are available for the most current month and annual averages only. The following instructions will assist users in calculating data for other time periods.

Monthly labor force data for sub-county areas are calculated by using the share of county-level employment and unemployment in the area at the time of the most current five-year American Community Survey (ACS) estimates, which are updated annually. The sub-area’s employment and unemployment estimates are then added to determine the total labor force and unemployment rate.

This method assumes that the rates of change in employment and unemployment are exactly the same in each sub-county area as at the county level (the same process is used for unemployment). If this assumption is not true for a specific sub-county area, then the estimates for that area may not be representative of the current economic conditions. Since this assumption is untested, caution should be employed when using these data.

Find the Ratios

Locate the sub-county data file for the county in which the sub-county area is located. You may want to view the file to verify that the area you need is available. The data in this file should look like this:

  


                       Labor  Employ-   Unemployment  Emp       Unemp
Area Name                Force     ment   Number  Rate  Ratio     Ratio
Column                    (1)      (2)    (3)    (4)    (5)       (6)

Amador County           18,900   17,400   1,500   7.7%  1.000000  1.000000

Amador City - city         200      200       0   4.2%  0.009184  0.004839
Ione - city              1,900    1,800     100   5.7%  0.100661  0.072581
Jackson - city           2,600    2,400     200   6.8%  0.138134  0.119355
Plymouth - city            500      500       0   2.5%  0.031227  0.009677
Sutter Creek - city      1,500    1,400     100   9.3%  0.081337  0.100000

At this point, you may want to write down the employment and unemployment ratios in columns (5) and (6), or save the entire document for future reference. These ratios will remain constant until the next decennial federal census.

Find County Data

Now find the county labor force file containing employment and unemployment data for the time period of interest to you. The best files to use are the historical data available on the Labor Force page. These files are available for individual counties. Here is a sample of this file:


Civilian Labor Force, Employment, and Unemployment 

Amador County

March 2007 Benchmark;  Data are not seasonally adjusted

Notes:  1) The unemployment rate is calculated using unrounded data.
        2) Labor force data for all geographic areas for 1990 to 2007 now reflect the March 2007
           
annual revision (or benchmark) and Census 2000 population controls at the state level.

Source:  Employment Development Department, Labor Market Information
         Division, 916-262-2162, www.labormarketinfo.edd.ca.gov

    2008       Labor Force     Employment   Unemployment   U.E. Rate
 January            18,240         16,870          1,370        7.5%
February            18,220         16,920          1,300        7.2%
   March            18,320         16,940          1,380        7.5%

You can also find the county data in "Labor Force Data for Counties Report". These reports list labor force data for all counties by month.

Calculate City Data

To calculate sub-county area labor force data, multiply the county employment and unemployment figures by the respective employment and unemployment ratios for the desired sub-area. The results represent the employment and unemployment for the sub-area for that time period.

Civilian labor force is the sum of the area’s employment and unemployment. The unemployment rate is calculated by dividing unemployment by the civilian labor force then multiply by 100.

EXAMPLE:
Using the data above, calculate the unemployment rate for the City of Ione in Amador County for January 2008.

Ratios for City of Ione (2000 Census): Employment: 0.100661 Unemployment: 0.072581	Data for Amador County (January 2008): Employment: 16,870 Unemployment: 1,370
Calculations for City of Ione for January 2008: Employment: 0.100661 * 16,870 = 1,698 Unemployment: 0.072581 * 1,370 = 99 Civilian Labor Force: 1,698 + 99 = 1,797 Unemployment Rate: (99 / 1797) x 100 = 5.5%