Technical Note
Scope of the survey
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. OES data
available from BLS include cross-industry occupational employment and
wage estimates for the nation; over 500 areas, including states and the
District of Columbia, metropolitan statistical areas (MSAs), metropolitan
divisions, nonmetropolitan areas, and territories; national industry-
specific estimates at the NAICS sector, 3-, 4-, and selected 5-digit
industry levels; and national estimates by ownership across all
industries and for schools and hospitals.
The OES survey is a cooperative effort between BLS and the State
Workforce Agencies (SWAs). BLS funds the survey and provides the procedures
and technical support, while the State Workforce Agencies collect most
of the data. OES estimates are constructed from a sample of about 1.2
million establishments. Each year, forms are mailed to two semiannual
panels of approximately 200,000 sampled establishments, one panel in May
and the other in November. May 2011 estimates are based on responses from
six semiannual panels collected over a 3-year period: May 2011, November
2010, May 2010, November 2009, May 2009, and November 2008. The overall
national response rate for the six panels is 77.3 percent based on
establishments and 73.3 percent based on employment. The unweighted
employment of sampled establishments across all six semiannual panels
represents approximately 62.2 percent of total national employment.
The occupational coding system
The OES survey categorizes workers into nearly 800 detailed occupations
based on the Office of Management and Budget’s Standard Occupational
Classification (SOC) system; together, these detailed occupations make up
22 of the 23 SOC major occupational groups. Major group 55, Military
Specific Occupations, is not included. The May 2011 and May 2010 OES
estimates are based in part on data collected using the 2010 SOC system.
Previous estimates were based on the 2000 SOC.
Almost all the occupations in this release are 2010 SOC occupations;
however, some are not. In these cases, an estimate for a temporary
occupation was created from data reported for one or more occupations
in the 2000 SOC combined with data reported for one or more 2010 SOC
occupations. Some occupations have the same title as a 2010 SOC
occupation, but not the same content. These occupations are marked with
an asterisk (*) and given a temporary code for the OES data. The May 2012
OES data will reflect the full set of detailed occupations in the 2010
SOC. For a list of all occupations, including 2010 SOC occupations, and
how data collected on two structures were combined, see the OES Frequently
Asked Questions online at www.bls.gov/oes/oes_ques.htm#Ques41.
For more information about the SOC system, please see the Bureau of Labor
Statistics website at www.bls.gov/soc/.
The industry coding system
The OES survey uses the 2007 North American Industry Classification
System (NAICS). For more information about NAICS, see the BLS website
at www.bls.gov/bls/naics.htm.
The OES survey excludes the majority of the agricultural sector, with
the exception of logging (NAICS 113310), support activities for crop
production (NAICS 1151), and support activities for animal production
(NAICS 1152). Private households (NAICS 814) also are excluded. OES
federal government data include the U.S. Postal Service and the federal
executive branch only. All other industries, including state and local
government, are covered by the survey.
The OES survey covers all full- and part-time wage and salary workers in
nonfarm industries. The survey does not include the self-employed, owners
and partners in unincorporated firms, household workers, or unpaid family
workers.
Survey sample
The OES survey draws its sample from state unemployment insurance (UI)
files. Supplemental sources are used for rail transportation (NAICS 4821)
and Guam because they do not report to the UI program. The OES survey
sample is stratified by metropolitan and nonmetropolitan area, industry,
and size.
To provide the most occupational coverage, larger employers are more
likely to be selected than smaller employers. An annual census is taken
of the executive branch of the federal government, the U.S. Postal
Service, and state government.
Concepts
Occupational employment is the estimate of total wage and salary
employment in an occupation. The OES survey defines employment as the
number of workers who can be classified as full- or part-time employees,
including workers on paid vacations or other types of paid leave; workers
on unpaid short-term absences; salaried officers, executives, and staff
members of incorporated firms; employees temporarily assigned to other
units; and employees for whom the reporting unit is their permanent duty
station, regardless of whether that unit prepares their paycheck.
Wages for the OES survey are straight-time, gross pay, exclusive of
premium pay. Base rate; cost-of-living allowances; guaranteed pay;
hazardous-duty pay; incentive pay, including commissions and production
bonuses; and tips are included. Excluded are overtime pay, severance pay,
shift differentials, nonproduction bonuses, employer cost for
supplementary benefits, and tuition reimbursements.
OES receives wage rate data for the federal government, the U.S. Postal
Service, and some state governments. For the remaining establishments,
the OES survey collects wage data in 12 intervals. For each occupation,
respondents are asked to report the number of employees paid within
specific wage intervals. The intervals are defined both as hourly rates
and the corresponding annual rates, where the annual rate for an
occupation is calculated by multiplying the hourly wage rate by a typical
work year of 2,080 hours. The responding establishments are instructed to
report the hourly rate for part-time workers, and to report annual rates
for occupations that are typically paid at an annual rate but do not work
2,080 hours per year, such as teachers, pilots, and flight attendants.
Other workers, such as some entertainment workers, are paid hourly rates,
but generally do not work 40 hours per week, year round. For these
workers, only an hourly wage is reported.
Estimation methodology
The OES survey is designed to produce estimates by combining six panels
of data collected over a 3-year period. Each OES panel includes
approximately 200,000 establishments. The full six-panel sample of nearly
1.2 million establishments allows the production of estimates at detailed
levels of geography, industry, and occupation.
Wage updating. Significant reductions in sampling errors are obtained by
combining six panels of data, particularly for small geographic areas and
occupations. Wages for the current panel need no adjustment. However,
wages in the five previous panels need to be updated to the current
panel's reference period.
The OES program uses the BLS Employment Cost Index (ECI) to adjust survey
data from prior panels before combining them with the current panel's
data. The wage updating procedure adjusts each detailed occupation's wage
rate, as measured in the earlier panel, according to the average movement
of its broader occupational division.
Imputation. About 20 percent of establishments do not respond for a given
panel. A "nearest neighbor" hot deck imputation procedure is used to
impute missing occupational employment totals. A variant of mean imputation
is used to impute missing wage distributions.
Weighting and benchmarking. The sampled establishments are weighted to
represent all establishments for the reference period. Weights are
further adjusted by the ratio of employment totals (the average of
November 2010 and May 2011 employment) from the BLS Quarterly Census of
Employment and Wages to employment totals from the OES survey.
For more information
Answers to frequently asked questions about the OES data are available at
www.bls.gov/oes/oes_ques.htm. Detailed technical information about the
OES survey is available in our Survey Methods and Reliability Statement
on the BLS website at www.bls.gov/oes/current/methods_statement.pdf.
