Employment Cost Index Technical Note
Last Modified Date: October 31, 2018
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
Data for the September 2018 reference period were collected from a probability sample of approximately 27,000
occupational observations selected from a sample of about 6,500 private industry establishments and
approximately 7,900 occupational observations selected from a sample of about 1,400 state and local government
establishments that provided data at the initial interview.
To assist users in ascertaining the reliability of Employment Cost Index (ECI) series, standard errors of all
current quarter not seasonally adjusted 3- and 12-month percent change series are also available, see
www.bls.gov/ncs/ect/ectvar.htm and the public data query tools at www.bls.gov/ncs/ect/data.htm. 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.
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