Employment Cost Index Technical Note

					    TECHNICAL NOTE

The Employment Cost Index (ECI) measures the change in the cost of labor, free from the influence of 
employment shifts among occupations and industries. Detailed information on survey concepts, coverage, 
methods, nonresponse adjustment, and imputation can be found in the BLS Handbook of Methods, Chapter 8, 
“National Compensation Measures,” at www.bls.gov/opub/hom/pdf/homch8.pdf.

Sample size

Data for the September 2017 reference period were collected from a probability sample of approximately 27,500 
occupational observations selected from a sample of about 6,700 private industry establishments and 
approximately 8,100 occupational observations selected from a sample of about 1,400 state and local government 
establishments that provided data at the initial interview.

Standard errors

To assist users in ascertaining the reliability of Employment Cost Index (ECI) series, standard errors of all 
current quarter estimates except seasonally adjusted series are made available shortly after publication of 
the news release. Standard errors provide users a measure of the precision of an estimate to ensure that it is 
within an acceptable range for their intended purpose. For further information see 
www.bls.gov/ncs/ect/ectvar.htm.

Historical listings

Historical listings that provide all ECI data are available at www.bls.gov/ect/#tables. Included among these 
listings is one that provides continuous occupational and industry series. This listing uses the Standard 
Industrial Classification Manual and Occupational Classification System series through 2005 and the North 
American Industry Classification System and Standard Occupational Classification from 2006 to the present. It 
provides the official series from the beginning of the ECI in 1975 through the current quarter. For more 
information on the criteria used in defining continuous series, see the article published in the Monthly Labor 
Review at www.bls.gov/opub/mlr/2006/04/art2full.pdf.

Employer Costs for Employee Compensation data

The costs per hour worked of compensation components are published in a separate news release titled "Employer 
Costs for Employee Compensation" (ECEC). These releases are issued 3 months after the reference period. The 
ECEC release dates are available at www.bls.gov/schedule/2017/home.htm. Historical ECEC data are available in 
summary documents at www.bls.gov/ect/#tables. Since the ECEC is calculated with current employment weights 
rather than the fixed weights used in computing the ECI, year-to-year changes in the cost levels usually 
differ from those in the ECI. For additional information on the use of fixed employment weights in computing 
the ECI, see www.bls.gov/opub/mlr/2016/article/introducing-2012-fixed-employment-weights-for-the-employment-
cost-index.htm.

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Last Modified Date: October 31, 2017