March 2013

Changes in the publication of seasonally adjusted Employment Cost Index series

E. Raphael Branch

Various factors have influenced the publication of ECI seasonally adjusted series, increasing the number of series published; these factors include the transition to NAICS and SOC, new publication procedures, the seasonal status of a series, and improvements in ECI processing Since the first seasonally adjusted Employment Cost Index (ECI) data were published in the December 1990 ECI news release, which contained 33 seasonally adjusted series, the Bureau of Labor Statistics (BLS) has periodically introduced improvements to the publication of ECI seasonally adjusted data. That first release of data included a total of 43 series in the seasonally adjusted data table, 10 of which were not seasonally adjusted because no measurable seasonality was found. In September 1991, 3 more series were added to the list of candidates for seasonal adjustment, and 37 of the 46 series published in the seasonal adjustment table were seasonally adjusted. From September 1991 through 2005, the year before major changes were introduced into the ECI, the number of series published in the seasonal adjustment table remained the same, at 46, and by 2005, 44 of them were seasonally adjusted. Except for the additions in 1991, from 1990 through 2005 changes in the number of seasonally adjusted series were due solely to changes in the seasonal status of the series. Beginning with the March 2006 estimates, however, changes in the publication of seasonally adjusted series were due not only to changes in the seasonal status of a series, but also to changes in how ECI data are classified, published, and processed. As of 2012, the ECI news release contains 136 candidate series for seasonal adjustment, and 132 seasonally adjusted series are published each quarter, providing users with more extensive information on changes in the cost of wages and benefits, free from the effects of events that follow regular patterns each year. This article describes the changes implemented by BLS and their effect

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