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Reweighting and Recoding in the ECI

The Employment Cost Index (ECI) measures the change in compensation costs while controlling for any employment shifts among occupational and industry groups. Occupational and industry classification systems and weights are used to ensure these groups are held constant over time. The ECI’s weights are changed periodically after remaining fixed for a number of years. Because the ECI’s employment weights remain fixed for long periods, it is possible for the fixed weights to differ significantly from the current weighting of the economy. Implementing updated coding systems and weights helps ensure that the ECI remains relevant.

Fixed weight updates

There are two types of weights used in the ECI: sample weights and fixed weights. Sample weights apply to each surveyed occupation within an establishment and represent the inverse probability of selection. Fixed weights are applied to the compensation costs of an occupational group within an industry group. These weights represent the occupational and industry employment counts at one point in time, and are held constant within the ECI until the next reweight.

History of Fixed Weight Updates in the ECI
Fixed Weight Source	Published Estimates
1970 Census of Population	March 1976 – March 1986
1980 Census of Population	June 1986 – December 1994
1990 Occupational Employment and Wage Statistics	March 1995 – December 2005
2002 Occupational Employment and Wage Statistics	March 2006 – September 2013
2012 Occupational Employment and Wage Statistics	December 2013 – September 2022
2021 Occupational Employment and Wage Statistics	December 2022 – Present

What changed with each reweight?

1970 Census of Population▸
- The 1970 Census of Population from the Census Bureau was used when the ECI was first published in June 1976.
1980 Census of Population▸
- Beginning with the June 1986 ECI, the 1980 Census of Population from the Census Bureau replaced the 1970 Census of Population. At the level at which ECI occupational indexes were published, the 1980 census definitions of the major occupational groups were similar to those for the 1970 census. Some detailed occupations that were defined in both 1970 and 1980 were shifted to a different major occupational group between the two years. For more information on the reweight, see Introducing new weights for the Employment Cost Index.
1990 Occupational Employment and Wage Statistics▸
- Beginning with the March 1995 ECI, 1990 employment counts primarily from the BLS Occupational Employment and Wage Statistics program replaced the 1980 Census of Population. A report on the reweighting, "Introducing 1990 Weights for the ECI," from the June 1995 issue of Compensation and Working Conditions is available upon request.
2002 Occupational Employment and Wage Statistics▸
- Beginning with the March 2006 ECI, 2002 employment counts primarily from the BLS Occupational Employment and Wage Statistics program, supplemented by data from the QCEW program, replaced the 1990 employment counts. This coincided with a transition to new occupational and industry classification systems, as well as a rebase setting December 2005 equal to 100, see Change is coming to the ECI. For more information on the reweight, see Introducing 2002 weights for the Employment Cost Index.
2012 Occupational Employment and Wage Statistics▸
- Beginning with the December 2013 ECI, 2012 employment counts primarily from the BLS Occupational Employment and Wage Statistics program, supplemented by data from the QCEW program, replaced the 2002 employment counts. For more information on the reweight, see Introducing 2012 fixed employment weights for the Employment Cost Index.
2021 Occupational Employment and Wage Statistics▸
- Beginning with the December 2022 ECI, 2021 employment counts from the Occupational Employment and Wage Statistics program will replace 2012 weights. For more information on the reweight, see Introducing 2021 fixed employment weights and 2018 SOC codes for the Employment Cost Index.

Industry classification updates

The ECI currently uses the North American Industry Classification System (NAICS) to aid in sampling establishments as well as publishing data by industry. In order to reflect current industries, this classification is periodically updated.

History of Industry Classification Updates in the ECI
Classification System	Published Estimates
1972 Standard Industrial Classification	March 1976 – December 1990
1987 Standard Industrial Classification	March 1991 – December 2005
2002 North American Industry Classification System	March 2006 – September 2007
2007 North American Industry Classification System	December 2007 – September 2013
2012 North American Industry Classification System	December 2013 – March 2018
2017 North American Industry Classification System	June 2018 – December 2023
2022 North American Industry Classification System	March 2024 – Present

What changed with each new industry classification?

1972 SIC▸
- The 1972 Standard Industrial Classification (SIC) was used when the ECI was first published in June 1976.
1987 SIC▸
- The 1987 Standard Industrial Classification (SIC) was first used in the March 1991 ECI. This was the last revision of the SIC industry classification by the United States government. Over 1,100 changes were recommended by different groups such as businesses and government agencies. These revisions included creating new industries, consolidating others, and changing the boundaries of industry groups to reflect how the economy had changed.
2002 NAICS▸
- The 2002 North American Industry Classification System (NAICS) was first used in the March 2006 ECI. It was adopted 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. The switch introduced new series, discontinued some series, and made some series from the 1987 SIC structure either continuous or not continuous with the new series. For more information on the continuous and not continuous series as well as the criteria for determining them, see Change in coming to the ECI.
2007 NAICS▸
- The 2007 North American Industry Classification System (NAICS) was first used in the December 2007 ECI. This conversion resulted in small changes to definitions for manufacturing, telecommunications, financial activities, and professional and technical services. Updates were also done to several industry titles and descriptions. Differences between the two NAICS systems did not affect any of the published ECI series.
2012 NAICS▸
- The 2012 North American Industry Classification System (NAICS) was first used in the December 2013 ECI. This conversion resulted in small changes to the content of manufacturing and retail trade sectors. It also had minor changes in the coding in the utilities and the leisure and hospitality sectors. Updates were also done to several industry titles and descriptions.
2017 NAICS▸
- The 2017 North American Industry Classification System (NAICS) was first used in the June 2018 ECI. This conversion did not have a noticeable effect on the data.
2022 NAICS▸
- The 2022 North American Industry Classification System (NAICS) was first used in the March 2024 ECI. This conversion did not have a noticeable effect on the data.

Occupational classification updates

The ECI currently uses the Standard Occupational Classification (SOC) system to aid in sampling jobs as well as publishing data by occupational group. In order to reflect the most up to date occupations in the economy, the classification is periodically updated based on the Census of Population.

History of Occupational Classification Updates in the ECI
Classification System	Published Estimates
1970 Occupational Classification System	March 1976 – March 1986
1980 Occupational Classification System	June 1986 – December 1994
1990 Occupational Classification System	March 1995 – December 2005
2000 Standard Occupational Classification	March 2006 – September 2013
2010 Standard Occupational Classification	December 2013 – September 2022
2018 Standard Occupational Classification	December 2022 - Present

What changed with each new occupational classification?

1970 OCS▸
- The 1970 Occupational Classification System (OCS) was based on the Census of Population and was used when the ECI was first published in June 1976. For 1970, the occupational classification included 441 occupational categories.
1980 OCS▸
- The 1980 Occupational Classification System (OCS) was first used with the June 1986 ECI. It had 503 occupational categories, an increase of 14 percent from 1970. The 1980 OCS was a major departure from earlier censuses because it was developed to be consistent with the 1980 Standard Occupational Classification (SOC) manual. The 1980 OCS had 13 major occupational groups that mapped into the 20 SOC divisions.
1990 OCS▸
- The 1990 Occupational Classification System (OCS) was first used with the March 1995 ECI release, and it is based on the 1990 Census of Population and Housing Classified Index of Industries and Occupations. The Census Index classifies occupations into about 500 occupation classifications within 13 major group categories.
2000 SOC▸
- The 2000 Standard Occupational Classification (SOC) system replaced the 1990 OCS beginning with the March 2006 ECI release, based on the Census of Population. The white-collar and blue-collar occupational series were discontinued in 2007 and occupational series were presented by the aggregate groups specified in the SOC manual. The 2000 SOC had 821 detailed occupations.For more information on the discontinuous series as well as the criteria for determining them, see Change in coming to the ECI.
2010 SOC▸
- The 2010 Standard Occupational Classification (SOC) system was first used with the December 2013 ECI release. It contains 840 detailed occupations, aggregated in 461 broad occupations. There are 97 minor occupational groups and 23 major groups, The 2010 SOC revision process resulted in both major and minor changes to the 2000 SOC, with significant updates to information technology, healthcare, and human resource occupations.
2018 SOC▸
- The 2018 Standard Occupational Classification (SOC) system was first used with the December 2022 ECI. A number of series were found to be discontinuous between the 2010 and 2018 SOC. For more information on the change in coding, see Introducing 2021 fixed employment weights and 2018 SOC codes for the Employment Cost Index.

More Information

For more information on the industry and occupational classification systems, see Classification systems used by the National Compensation Survey (NCS).

Last Modified Date: April 22, 2024