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 this reference period were collected from a probability sample of approximately 
23,300 occupational observations selected from a sample of about 5,500 private industry establishments 
and approximately 7,500 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 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/eci/factsheets/eci-standard-errors.htm and the database query tool at 
www.bls.gov/eci/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: Historical ECI data are available in xlsx format at www.bls.gov/eci/tables.htm.
The continuous occupational and industry series listing uses the Standard Industrial Classification 
(SIC) Manual and Occupational Classification System (OCS) series from 1975 through 2005 and the North 
American Industry Classification System (NAICS) and Standard Occupational Classification (SOC) 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. The transition from
NAICS 2017 to NAICS 2022 occurred during the March 2024 ECI and series were determined to remain 
continuous. 

Employer Costs for Employee Compensation data: The costs per hour worked of compensation components are
published as part of the Employer Costs for Employee Compensation (ECEC) news release. The ECEC release
dates are available at www.bls.gov/schedule/news_release/ecec.htm. Historical ECEC data are available in
xlsx format at www.bls.gov/ecec/tables.htm. 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. Beginning with the December 2022 release, the ECI introduced new employment 
weights, see www.bls.gov/eci/notices/2022/eci-2021-fixed-weights-and-2018-soc-update.htm.

Seasonal factors: Detailed information on seasonal factors for the 2024 reference year and the revisions
of historical seasonally adjusted data for the most recent five years can be found at www.bls.gov/eci/
factsheets/annual-seasonal-adjustment.htm. More information on seasonal adjustment can be found at 
www.bls.gov/opub/mlr/2024/article/seasonality-in-the-employment-cost-index.htm. 

Additional information: Historical tables are available in xlsx format for constant dollar, current
dollar, and continuous series, see www.bls.gov/eci/tables.htm. ECI release dates are available on the
release calendar at www.bls.gov/schedule/news_release/eci.htm. Subscribe to receive the BLS Economic 
News Release email at public.govdelivery.com/accounts/USDOLBLS/subscriber/new. If you are deaf, hard of
hearing, or have a speech disability, please dial 7-1-1 to access telecommunications relay services.