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. For information on survey concepts, coverage, methods, nonresponse
adjustment, and imputation see National Compensation Measures Handbook of Methods at
www.bls.gov/opub/hom/ncs/home.htm.

Sample size

Data for the March 2018 reference period were collected from a probability sample of approximately 27,300
occupational observations selected from a sample of about 6,600 private industry establishments and
approximately 8,000 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 also available, 
see www.bls.gov/ncs/ect/ectvar.htm. Standard errors provide users a measure of the precision ofan estimate 
to ensure that it is within an acceptable range for their intended purpose.

Historical listings

Historical listings are available at www.bls.gov/ect/#tables. The continuous occupational and industry series
listing uses the Standard Industrial Classification Manual and Occupational Classification System series from 
1975 through 2005 and the North American Industry Classification System and Standard Occupational 
Classification from 2006 to the present. It provides the official series deemed continuous after the change 
in classification systems. 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). The ECEC release dates are available at 
www.bls.gov/schedule/2018/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.

Fixed Employment Weights

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: April 27, 2018