What are the differences between the quarterly hourly compensation measures and the Employment Cost Index (ECI)?
The ECI and the hourly compensation measures may differ because they are designed to measure two different things. There is no formal analysis of the differences between the ECI and those in the hourly compensation series, largely because most of the differences are not quantifiable. One quantifiable difference, however, is the presentation of percent changes between adjacent periods. Both series present their data as index numbers, one-quarter or 3-month percent change, and four-quarter or 12-month percent change. The index numbers and year-over-year comparisons are consistent; however the one-quarter or 3-month percent changes are presented differently. ECI presents these data as the actual change over the 3-month period while the hourly compensation measures are presented at a compound annual rate of change (i.e., as if the same percent change were to continue for four quarters). Some of the other differences between the ECI and hourly compensation for all persons in the nonfarm bus
