The Occupational Employment Statistics (OES) survey is a semiannual mail survey measuring occupational employment and wage rates for wage and salary workers in nonfarm establishments in the United States, Guam, Puerto Rico, and the Virgin Islands are also surveyed, but their data are not included in this release. Nationally, OES estimates are constructed from a sample of about 1.2 million establishments. Forms are mailed to approximately 200,000 establishments in May and November of each year for a 3-year period.
OES is not a time series, it is a panel to panel series. Changes in the occupational, industrial, and geographical classification systems, the way data is collected, in the survey reference period, and changes in mean wage estimation methodology, as well as permanent features of the methodology, make it less useful for time comparisons.