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 BLS Handbook of Methods, 
Chapter 8, “National Compensation Measures,” Bureau of Labor Statistics, on the Internet at 

Sample size

Data for the March 2015 reference period were collected from a probability sample of approximately 
37,400 occupational observations selected from a sample of about 8,600 private industry establishments 
and approximately 8,900 occupational observations selected from a sample of about 1,500 state and 
local government establishments that provided data at the initial interview.

Health insurance data

Data from the ECI that provide 12-month percent changes in employer costs for health insurance in 
private industry are available at www.bls.gov/web/eci/echealth.pdf.

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 Census of Population 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, based on data from the ECI, are published in a 
separate news release titled "Employer Costs for Employee Compensation" (ECEC). The next ECEC 
release is scheduled for 10:00 a.m. (EDT), Wednesday, June 10, 2015. 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.

Seasonal Adjustment Revisions

Each year data series are reviewed for seasonal patterns. When seasonality is found, data are published 
as a seasonally adjusted series. Based on this review for 2015, the seasonally adjusted private industry 
service occupations wages and salaries series was dropped, while a seasonally adjusted series for private 
industry nursing and residential care facilities wages and salaries was added. Historical data for the latter 
series, beginning with March 2010, are now available. For additional information regarding the annual 
seasonal adjustment process please visit www.bls.gov/ncs/ect/ectsfact.htm.

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Last Modified Date: April 30, 2015