This section provides basic information on survey procedures and concepts. For a more complete description, see the BLS Handbook of Methods, Chapter 8, "National Compensation Measures," on the Internet at www.bls.gov/opub/hom/ncs/.
Survey scope
The NCS covers establishments employing one worker or more in private goods-producing industries (mining, construction, and manufacturing); private service-providing industries (trade, transportation, and utilities; information; financial activities; professional and business services; education and health services; leisure and hospitality; and other services); State governments; and local governments. Agriculture, forestry, fishing and hunting, private households, and the Federal government are excluded from the scope of the survey. For purposes of this survey, an establishment is an economic unit that produces goods or services, a central administrative office, or an auxiliary unit providing support services to a company. For private industries in the survey, the establishment is usually at a single physical location. For State and local governments, an establishment is defined as an agency or entity such as a school district, a college, a university, a hospital, a nursing home, an administrative body, a court, a police department, a fire department, a health or social service operation, a highway maintenance operation, an urban transit operation, or some other governmental unit within a defined geographic area or jurisdiction.
Sampling frame
The list of establishments from which the survey sample is selected (the sampling frame) is developed from State unemployment insurance reports. Due to the volatility of industries within the private sector, the most recent month of reference available at the time the sample is selected is used to develop sampling frames. Approximately one-fifth of the private industry sample is reselected each year. The sampling frame for State and local government establishments is revised every 10 years.
Data collection
The collection of data from survey respondents requires detailed procedures. Field economists collect the data by contacting each establishment in the survey.
Industry classification
The NCS sample is classified by the NAICS. For more detail on NAICS, see www.bls.gov/bls/naics.htm. The NCS began collecting and coding data under NAICS 2007 in August 2007. Some of the data in this bulletin were collected under NAICS 2002. NAICS 2007 includes revisions to NAICS 2002 that affect several sectors. The most significant revisions are in the information sector, particularly within the telecommunications area. For more information about the differences between the NAICS 2002 and NAICS 2007, see www.census.gov/eos/www/naics.
Occupational selection and classification
The Standard Occupational Classification (SOC) system is used by all Federal statistical agencies. NCS data are currently classified according to the 2000 edition of the SOC manual. Workers are classified into detailed occupational categories with standardized definitions. To facilitate classification, occupations are combined to form major groups, minor groups, and broad occupations. Each item in the hierarchy is designated by a six-digit code. Major group codes end with 0000, minor groups codes end with 000, and broad occupations codes end with 0. (See the entire list of SOC occupational categories at www.bls.gov/soc. Note that the NCS excludes major group 23 (23-0000), military-specific occupations. )
Identification of the occupations for which wage data are to be collected is a multi-step process:
- Selection of establishment jobs by probability proportional to size
- Classification of jobs into occupations based on the SOC system
- Characterization of jobs as full-time or part-time, union or nonunion, and time or incentive
- Determination of the level of work of each job
For each occupation, wage data are collected for those workers whose jobs can be characterized by the criteria identified in the last three steps. If a specific work level cannot be determined, wages are still collected. In step one, the jobs to be sampled are selected at each establishment by the BLS field economist. A complete list of employees is used for sampling, with each worker selected representing a job within the establishment. As with the selection of establishments, the selection of a job is based on probability proportional to its size in the establishment. The greater the number of people working in a job in the establishment, the greater is its chance of selection. The number of jobs for which data are collected in each establishment is based on the establishment's employment size. The number of jobs selected follows this schedule:
Number of employees | Number of jobs selected |
149 | Up to 4 |
50249 | 6 |
250 or more | 8 |
Exceptions include State and local government units, for which up to 20 jobs may be selected, and the aircraft manufacturing industry unitsthose matching NAICS code 33-6411for which up to 32 jobs may be selected.
The second step of the process entails classifying the selected jobs into occupations based on their duties. A job may fall into any one of about 800 occupational classificationsfrom accountant to zoologistbased on the 2000 SOC system. When workers can be classified into more than one occupation, they are classified into the occupation that requires the higher skill level. When there is no perceptible difference in skill level, the workers are classified into the occupation that describes their primary activity. Each occupational classification is an element of a broader classification known as a major group. Occupations can fall into any of 22 major groups; military occupations are excluded from the survey. The Web site page with URL www.bls.gov/soc contains a complete list of all individual occupations, classified by the major group to which they belong.
In step 3, certain other job characteristics of the chosen worker are identified. First, the worker is identified as holding either a full-time job or a part-time job, based on the establishments definition of those terms. Then, the worker is classified as having a time or an incentive job, depending on whether any part of the pay was based directly on the actual production of the worker, rather than solely on hours worked. Finally, the worker was identified as being in a union job or a nonunion job.
Union workers. The NCS defines a union worker as any employee in a union occupation when all of the following conditions are met: a labor organization is recognized as the bargaining agent for all workers in the occupation; wage and salary rates are determined through collective bargaining or negotiations; and settlement terms, which must include earnings provisions and may include benefit provisions, are embodied in a signed, mutually binding collective bargaining agreement. A nonunion worker is an employee in an occupation not meeting the conditions for union coverage.
Supervisory occupations. Supervisors usually assign and review the work of subordinates. Typically, supervisors have the authority to hire, transfer, lay off, promote, reward, and discipline other employees. By NCS definitions, first-line supervisors direct their staff through face-to-face meetings and are responsible for conducting the employees' performance appraisals. Second-line supervisors typically direct the actions of their staffs through first-line supervisors.
Work levels
In the last step before wage data are collected, a point factor leveling process is used to determine the work level of each job selected. Work level is a ranking within an occupation, based on the requirements of the position. Point factor leveling matches certain aspects of a job to specific levels of work with assigned point values. Points for each factor are then totaled to determine the overall work level for the job. The four occupational leveling factors are
- Knowledge
- Job controls and complexity
- Contacts (nature and purpose)
- Physical environment
For a complete description of point factor leveling, refer to the publication "National Compensation Survey: Guide for Evaluating Your Firm's Jobs and Pay," on the Internet at www.bls.gov/ocs/publications/pdf/national-compensation-survey-special-wage-studies-ncbr0004.pdf.
Combined work levels
This bulletin includes a table that simplifies the presentation of work levels by combining them into four broad groups. The groups are determined by combinations of knowledge, job controls and complexity, contacts, physical environment, and supervisory duties and are meant to be comparable across different occupations. The broad groups and the combined work levels are as follows:
Group designation | Combined levels |
Group I | Levels 14 |
Group II | Levels 58 |
Group III | Levels 912 |
Group IV | Levels 1315 |
Areas surveyed
The NCS program collects data in geographic areas defined by the U.S. Office of Management and Budget (OMB). (For a list of all areas included in the 2007 national earnings estimates, see Appendix C.) Although the NCS usually collects data from 152 areas to compile its national estimates, 227 areas were surveyed this year, as new areas are being phased into the sample and others are being phased out.
In the areas newly surveyed in 2007, data were collected only in State and local government establishments. Over the next 5 years, new areas will include private industry establishments to replenish the private industry sample. (For more information on the area definitions, see Jason Tehonica, "New Area Sample Selected for the National Compensation Survey," Compensation and Working Conditions Online, Apr. 25, 2005, on the Internet at www.bls.gov/opub/mlr/cwc/new-area-sample-selected-for-the-national-compensation-survey.pdf. For a list of current and historical OMB area definitions, see www.census.gov/programs-surveys/metro-micro.html.
Collection period
Survey data were collected over a 13-month period for the 87 larger areas; for the 140 smaller areas, data were collected over a 4-month period. For each establishment in the survey, the data reflect the establishments most recent information at the time of collection. The data for the National bulletin were compiled from locality data collected between December 2006 and January 2008. The average reference period is July 2007.
Earnings
Earnings are defined as regular payments from the employer to the employee as compensation for straight-time hourly work or for any salaried work performed. The following components are included as part of earnings:
- Incentive pay, including commissions, production bonuses, and piece rates
- Cost-of-living allowances
- Hazard pay
- Payments of income deferred due to participation in a salary reduction plan
- Deadhead pay, defined as pay given to transportation workers returning in a vehicle without freight or passengers
The earnings estimates for aircraft pilots and flight engineers (SOC code 53-2010) and detailed occupations within this group, and the earnings estimates for flight attendants (SOC code 39-6031), include flight pay and flight hours only; these estimates may not reflect the total earnings and hours worked.
The following forms of payments are not considered part of straight-time earnings:
- Shift differentials, defined as extra payment for working a schedule that varies from the norm, such as night or weekend work
- Premium pay for overtime, holidays, and weekends
- Bonuses not directly tied to production (such as Christmas and profit-sharing bonuses)
- Uniform and tool allowances
- Free or subsidized room and board
- Payments made by third parties (for example, tips)
- On-call pay
To calculate earnings for various periods (hourly, weekly, and annual), the NCS collects data on work schedules. For hourly workers, scheduled hours worked per day and per week, exclusive of overtime, are recorded. The number of weeks worked annually is determined as well. Because salaried workers who are exempt from overtime provisions often work beyond the assigned work schedule, the typical number of hours they actually worked is collected.
Processing and analyzing the data
Data are processed and analyzed at the BLS national office following collection. Processing and analysis includes weighting, adjusting for nonresponse, imputation, benchmarking, and calculating wage estimates, percentiles, variances, and other summary statistics.
Estimation, Weighting, and Nonresponse
The wage series in the tables are computed by combining the wages for each occupation sampled. Before being combined, individual wage rates are weighted by the number of workers; the sample weight, adjusted for nonresponding establishments and other factors; and the occupation's scheduled hours of work. The sample weight reflects the inverse of each unit's probability of selection at each sample selection stage and four weight adjustment factors:
- The first factor adjusts for initial establishment nonresponse.
- The second factor adjusts for initial occupational nonresponse.
- The third factor adjusts for any special situations that may have occurred during data collection.
- The fourth factor, poststratification, also called benchmarking, is applied to the raw data to adjust survey sample weights so that the weights reflect the current count of employment by industry to derive average hourly earnings. Initial weights are derived when the sample of establishments is selected, reflecting employment distribution by industry at that time. Those weights may be up to 7 years old. Benchmarking adjusts initial weights to reflect the employment distribution by industry at the reference date of the data.
The National Compensation Survey is voluntary, so a company official may refuse to participate in the initial survey or may be unwilling or unable to update previously collected data during a subsequent contact for one or more occupations. For those situations in which previous wage data cannot be updated, an estimate for the missing data is imputed, using information obtained from similar establishments and occupations.
Not all calculated series meet the criteria for publication. Before any series is published, it is reviewed to make sure that the number of observations underlying it is sufficient. This review prevents the publication of a series that could reveal information about a specific establishment. Estimates of the number of workers represent the total in all establishments within the scope of the study, not the number actually surveyed. Because occupational structures among establishments differ, estimates of the number of workers obtained from the sample of establishments indicate only the relative importance of the occupational groups studied.
Data reliability
The data in this report are estimates from a scientifically selected probability sample. Two types of errors are possible in an estimate based on a sample survey: sampling errors and nonsampling errors.
Sampling errors occur because observations come only from a sample and not from an entire population. The sample used for the NCS is one of a number of possible samples of the same size that could have been selected under the sample design. Estimates derived from the different samples would differ from one another. The standard error, or sampling error, is a measure of the variation among these differing estimates that indicates the precision with which an estimate from a particular sample approximates the average result of all possible samples. The relative standard error (RSE) is the standard error divided by the estimate. RSE data are provided alongside the earnings data in many of the presented tables in this report. The standard error can be used to calculate a confidence interval around a sample estimate. As an example, table 2 shows mean hourly earnings for all civilian full-time workers of $21.08 per hour and a relative standard error of 1.0 percent for this estimate. At the 90-percent level, the confidence interval for this estimate is from $20.73 to $22.43 ($21.08 × 1.645 × 0.010 = $0.346766, rounded to $0.35; $21.08 − 0.35 = $20.73; $21.08 + 0.35 = $21.43). In other words, if all possible samples were selected to estimate the population value, the interval from each sample would include the true population value approximately 90 percent of the time.
Nonsampling errors also affect survey results and they can stem from many sources, such as inability to obtain information for some establishments, difficulties with survey definitions, inability of the respondents to provide correct information, and mistakes in recording or coding the data obtained. Although not specifically measured for this report, the nonsampling errors were expected to be minimal due to the extensive training of the field economists who gathered the survey data, to computer edits of the data, and to a detailed data review.
Appendix B: Occupational Descriptions (PDF)
Appendix C: Survey Areas and Geographic Coverage
This appendix lists the 227 geographic areas surveyed under the NCS.
- Albany-Schenectady-Troy, NY
- Albuquerque, NM
- Allentown-Bethlehem-Easton, PA-NJ
- Amarillo, TX
- Anchorage, AK
- Andrews, TX
- Atlanta-Sandy Springs-Gainesville, GA-AL
- Atlantic City-Hammonton, NJ
- Auburn-Opelika, AL
- Augusta-Aiken, GA-SC
- Austin-Round Rock, TX
- Bangor, ME
- Bannock, ID
- Baton Rouge, LA
- Bedford, Fulton, and Juniata Counties, PA
- Billings, MT
- Birmingham-Hoover, AL
- Bloomington, IN
- Bloomington-Normal, IL
- Boston-Worcester-Manchester, MA-NH
- Bradenton-Sarasota-Venice, FL
- Bradley, TN
- Brainerd, MN
- Brownsville-Harlingen, TX
- Buffalo-Niagara-Cattaraugus, NY
- Caledonia and Orleans Counties, VT
- Carroll and Jo Daviess Counties, IL, and Lafayette County, WI
- Carson City, NV
- Cedar Rapids, IA
- Centralia, WA
- Charleston-North Charleston-Summerville, SC
- Charlotte-Gastonia-Concord, NC-SC
- Cheshire County, NH
- Cheyenne, CO
- Chicago-Naperville-Michigan City, IL-IN-WI
- Choctaw, AL
- Cincinnati-Middletown-Wilmington, OH-KY-IN
- Citrus County, FL
- Claremont, NH
- Clarksburg, WV
- Clatsop, OR
- Cleveland-Akron-Elyria, OH
- Clinton County, IA
- Clinton, NY
- Columbia County, NY
- Columbia, SC
- Columbus-Marion-Chillicothe, OH
- Corning, NY
- Corpus Christi, TX
- Craven, NC
- Crook County, OR
- Dallas-Fort Worth, TX
- Dayton-Springfield-Greenville, OH
- Decatur, GA
- Delta County, MI
- Denver-Aurora-Boulder, CO
- Des Moines, IA
- Detroit-Warren-Flint, MI
- Dorchester, MD
- El Paso, TX
- Elkhart-Goshen, IN
- Emporia, KS
- Esmeralda, Lyon, and Mineral Counties, NV
- Fairbanks-North Star, AK
- Fannin, Gilmer, and Lumpkin Counties, GA
- Fayette and Lee Counties, TX
- Fayetteville, NC
- Fergus, MT
- Ferry and Okanogan Counties, WA
- Fond Du Lac, WI
- Fort Collins-Loveland, CO
- Fort Walton Beach-Crestview-Destin, FL
- Franklin, VA
- Freeborn County, MN
- Fresno, CA
- Georgetown, SC
- Gillespie County, TX
- Goodhue, MN
- Grafton County, NH
- Grand Rapids-Wyoming, MI
- Great Falls, MT
- Green Lake, WI
- Greensboro-High Point, NC
- Greenville-Mauldin-Easley, SC
- Greenwood, SC
- Griggs, ND
- Harrison County, KY
- Hartford-West Hartford-Willimantic, CT
- Henderson, IL
- Henry, AL
- Hickory-Lenoir-Morganton, NC
- Holland-Grand Haven, MI
- Honolulu, HI
- Houston-Baytown-Huntsville, TX
- Huntsville-Decatur, AL
- Indianapolis-Anderson-Columbus, IN
- Iowa City, IA
- Jackson, MS
- Jacksonville, FL
- Jefferson County, IN
- Johnstown, PA
- Juneau, AK
- Juneau, WI
- Kalispell, MT
- Kansas City, MO-KS
- Kauai, HI
- Kennewick-Pasco-Richland, WA
- Knoxville, TN
- Lafayette, LA
- Lancaster, SC
- Las Vegas-Paradise, NV
- Lee, MS
- Lewis, MO
- Liberty, GA
- Lincoln, NE
- Lincoln, WY
- Little Rock-North Little Rock-Conway, AR
- Logan, NE
- Logansport, IN
- Los Angeles-Long Beach-Riverside, CA
- Louisville/Jefferson County-Elizabethtown-Scottsburg, KY-IN
- Madison, NE
- Madison, WI
- Manitowoc, WI
- Marshall, IN
- Meadville, PA
- Medford, OR
- Memphis, TN- MS-AR
- Miami, OK
- Miami-Fort Lauderdale-Pompano Beach, FL
- Milwaukee-Racine-Waukesha, WI
- Minneapolis-St. Paul-St. Cloud, MN-WI
- Mobile, AL
- Monroe, LA
- Monroe, OH
- Montgomery County, VA
- Moore County, NC
- Morgan County, IL
- Mount Airy, NC
- Murray, KY
- Muskegon-Norton Shores, MI
- Muskogee, OK
- Nashville-Davidson-Murfreesboro-Franklin, TN
- New Orleans-Metairie-Kenner, LA
- New York-Newark-Bridgeport, NY-NJ-CT-PA
- Nogales, AZ
- North Central Kansas
- Northumberland, PA
- Northwest Texas
- Norton City and Lee and Wise Counties, VA
- Ocala, FL
- Oklahoma City, OK
- Omaha-Council Bluffs, NE-IA
- Orange, VT
- Orlando-Kissimmee, FL
- Ottumwa, IA
- Paducah, KY-IL
- Palatka, FL
- Palm Bay-Melbourne-Titusville, FL
- Palo Pinto County, TX
- Panola, TX
- Philadelphia-Camden-Vineland, PA-NJ-DE-MD
- Phoenix-Mesa-Scottsdale, AZ
- Pittsburgh-New Castle, PA
- Polk County, NC
- Pope, AR
- Portland-Vancouver-Beaverton, OR-WA
- Prairie, AR
- Providence-New Bedford-Fall River, RI-MA
- Quincy, IL-MO
- Raleigh-Durham-Cary, NC
- Reading, PA
- Reno-Sparks, NV
- Richmond, VA
- Roanoke, VA
- Rochester, NY
- Rockford, IL
- Sacramento-Arden-Arcade-Truckee, CA-NV
- Salem, OR
- Salinas, CA
- Salisbury, MD
- Salt Lake City, UT
- San Antonio, TX
- San Diego-Carlsbad-San Marcos, CA
- San Jose-San Francisco-Oakland, CA
- Sanilac County, MI
- Sauk, WI
- Seattle-Tacoma-Olympia, WA
- Seneca County, OH
- Seward, NE
- Sioux City, IA-NE-SD
- Skagit County, WA
- Southeastern Nebraska-Northwestern Missouri
- Southwestern Mississippi
- Springfield, MA
- Springfield, MO
- St. Francis, AR
- St. Lawrence, NY
- St. Louis, MO-IL
- Starkville, MS
- State College, PA
- Tallahassee, FL
- Tama, IA
- Tampa-St. Petersburg-Clearwater, FL
- Tattnall County, GA
- Taylor, KY
- Toledo, OH
- Tucson, AZ
- Tulsa, OK
- Tunica, MS
- Tuscaloosa, AL
- Vermilion Parish, LA
- Virginia Beach-Norfolk-Newport News, VA-NC
- Visalia-Porterville, CA
- Ward, ND
- Wasco, OR
- Washington, GA
- Washington-Baltimore-Northern Virginia, DC-MD-VA-WV
- Wausau, WI
- Wayne, OH
- Wayne, TN
- Wilmington, NC
- Winston, MS
- Wooster, OH
- Yavapai County, AZ
- York-Hanover, PA
- Youngstown-Warren-Boardman, OH-PA