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Employee Benefits

Questions and Answers about the coming changes to the NCS benefits products

  1. How and when did the NCS benefit publications change?

    The following changes were introduced with the publication of the March 2007 estimates on August 22, 2007.

    • The 2002 North American Industry Classification System (NAICS) replaced the 1987 Standard Industrial Classification (SIC) system.
    • The 2000 Standard Occupational Classification System (SOC) replaced the 1990 Occupational Classification System (OCS) based on the Census of Population.
    • Additional imputation procedures were used to impute for missing data that was previously not imputed.
    • A new benchmark factor was introduced that uses data from two BLS programs.
  2. Why did the NCS benefit surveys change to the NAICS and SOC classification systems?

    The United States adopted NAICS and SOC as the standard industrial and occupational classification systems to be used by all Federal statistical agencies to provide a means of comparing data across agencies. NAICS was developed collaboratively with Mexico and Canada and is designed to provide comparability between the statistical systems of the three partners in the North American Free Trade Agreement (NAFTA).

    Information on NAICS and SOC, including background and definitions are available from the BLS websites: and

  3. How did the NCS benefit surveys change due to the adoption of NAICS and SOC?

    As a result of the switch in industry and occupational classifications, some new series have been introduced, some series have been discontinued, and some series from the old structure are either continuous or not continuous with new series. This is not the result of a change in what an establishment or the employees have been doing, but instead stems from a reclassification based on the new hierarchy.

  4. How do the NAICS industry series compare to SIC series?

    Two criteria were applied to determine if the new and old series were comparable. The first criterion is based on the overlap of employment between the two series. For example, a NAICS series is deemed comparable to the corresponding SIC series only if at least 90 percent of the employment in the NAICS classification is also in the SIC classification, and at least 90 percent of the employment in the SIC classification is also in the NAICS classification. A second test compared comparable access and participation estimates for NAICS and SIC. A series was considered continuous if 90 percent or more of the estimates were within 1 percentage point. All of the industry and occupational series that met the first overlap criteria also passed the second comparison test.

    Table 1 shows all of the NAICS industries that met the comparability tests with the previous SIC series.

    Table 1. Continuity of NCS Benefit Survey Industry series between the 2002 North American Industry Classification System (NAICS) and the 1987 Standard Industrial Classification (SIC)
    NAICS (code in parentheses) Series meet definition of continuity Break in series or new series

    All Private Industry Workers


    Goods-producing industries


    Service-providing industries 1


    All State and Local Government Workers


    1 Previously titled service-producing industries.

  5. How do the SOC occupational series compare to OCS series?

    Tests similar to those used for the industry series were used for the occupational series.

    Table 2 shows information for SOC occupational series.

    Table 2. Continuity of NCS Benefit Survey Occupational series between the 2000 Standard Occupational Classification (SOC) and 1990 Occupational Classification System (OCS)
    SOC (code in parentheses) Series meet definition of continuity Break in series or new series

    All Private Industry Workers


    Management, professional, and related (11-29)


    Service (31-39)


    Sales and office (41-43)


    Natural resources, construction, and maintenance (45-49)


    Production, transportation, and material moving (51-53)


    All State and Local Government Workers

  6. Will the white collar and blue collar occupational series be retained?

    No, the white collar and blue collar series were discontinued in 2007. Occupational series are presented by the aggregate groups specified in the 2000 SOC manual.

  7. What methodological changes were implemented for handling missing data?

    Starting with the publication of benefit estimates for March 2007, additional imputation procedures were introduced to impute for provisions that were previously not imputed. Since provisions that were not available are now imputed, the not determinable columns will no longer exist in such tables.

  8. How has the benchmarking of final weights changed?

    Benchmarking is the process of adjusting the weight of each establishment in the survey to match the distribution of employment by industry at the reference period. Because the sample of establishments used to collect benefits data was chosen over the past several years, establishment weights reflect their employment when selected. The benchmark process updates the weight based on current employment. The new benchmark factor being introduced uses data from two BLS programs: the Quarterly Census of Employment and Wages (QCEW) and the Current Employment Statistics (CES) program. Combined, these programs provide the appropriate industry coverage and currency of data needed to benchmark the weights. The NCS sample is drawn from the QCEW.

  9. How do I obtain more information on benefits?

    Information at the Internet site provides information from the BLS Handbook of Methods. Information is also available on the benefits Internet site at

  10. When will other NCS products be changing to NAICS and SOC?

    All of the NCS products except detailed benefits provisions data have been converted to NAICS and SOC. Data for State and local government are scheduled to be published using NAIC and SOC later in 2008. Private industry will be converted to NAIC and SOC in 2009.


Last Modified Date: April 14, 2008