This section presents statistics on the labor force; its distribution by occupation and industry affiliation; and the supply of, demand for, and conditions of labor. The chief source of these data is the Current Population Survey (CPS) conducted by the U.S. Census Bureau for the Bureau of Labor Statistics (BLS). Comprehensive historical and current data are available from the BLS Internet site <http://stats.bls.gov/cpshome.htm>. These data are published on a current basis by the BLS monthlypublication Employment and Earnings. Detailed data on the labor force are also available from the Census Bureau’s decennial census of population.

Types of data-Most statistics in this section are obtained by two methods: household interviews or questionnaires and reports of establishment payroll records. Each method provides data which the other cannot suitably supply. Population characteristics, for example, are readily obtainable only from the household survey, while detailed industrial classifications can be readily derived only from establishment records.

Household data are obtained from a monthly sample survey of the population. The CPS is used to gather data for the calendar week including the 12th of the month and provides current comprehensive data on the labor force (see text, Section 1, Population). The CPS provides information on the work status of the population without duplication since each person is classified as employed, unemployed, or not in the labor force. Employed persons holding more than one job are counted only once, according to the job at which they worked the most hours during the survey week.

Monthly, quarterly, and annual data from the CPS are published by the Bureau of Labor Statistics in Employment and Earnings. Data presented include national totals of the number of persons in the civilian labor force by sex, race, Hispanic origin, and age; the number employed; hours of work; industry and occupational groups; and the number unemployed, reasons for, and duration of unemployment. Annual data shown in this section are averages of monthly figures for each calendar year, unless otherwise specified.

The CPS also produces annual estimates of employment and unemployment for each state, 50 large metropolitan statistical areas, and selected cities. These estimates are published by BLS in its annual Geographic Profile of Employment and Unemployment. More detailed geographic data (e.g., for counties and cities) are provided by the decennial population censuses.

Data based on establishment records are compiled by BLS and cooperating state agencies as part of an ongoing Current Employment Statistics program. Survey data, gathered monthly from a sample of employers through mail questionnaires or electronic interviewing, are supplemented by data from other government agencies and adjusted at intervals to data from government social insurance program reports. The estimates exclude self-employed persons, private household workers, unpaid family workers, agricultural workers, and the Armed Forces. In March 1999, reporting establishments employed 8 million manufacturing workers (41 percent of the total manufacturing employment at the time), 19 million workers in private non-manufacturing industries (21 percent of the total in private non-manufacturing), and 15 million Federal, state, and local government employees (75 percent of total government).

The establishment survey counts workers each time they appear on a payroll during the reference period (as with the CPS, the week including the 12th of the month). Thus, unlike the CPS, a person with two jobs is counted twice. The establishment survey is designed to provide detailed industry information for the Nation, states, and metropolitan areas on non-farm wage and salary employment, average weekly hours, and average hourly and weekly earnings. Establishment survey data also arepublished inEmployment and Earnings.Historical national data are available on the site<http://stats.bls.gov/ces/home.htm>.

Labor force-According to the CPS definitions, the civilian labor force comprises all civilians in the non-institutional population 16 years and over classified as "employed" or "unemployed" according to the following criteria: Employed civilians comprise (a) all civilians, who, during the reference week, did any work for pay or profit (minimum of an hour’s work) or worked 15 hours or more as unpaid workers in a family enterprise and (b) all civilians who were not working but who had jobs or businesses from which they were temporarily absent for non-economic reasons (illness, weather conditions, vacation, labor-management dispute, etc.) whether they were paid for the time off or were seeking other jobs. Unemployed persons comprise all civilians who had no employment during the reference week, who made specific efforts to find a job within the previous 4 weeks (such as applying directly to an employer, or to a public employment service, or checking with friends) and who were available for work during that week, except for temporary illness. Persons on layoff from a job and expecting recall also are classified as unemployed. All other civilian persons, 16 years old and over, are "not in the labor force."

Beginning in 1982, changes in the estimation procedures and the introduction of 1980 census data caused substantial increases in the population and estimates of persons in all labor force categories. Rates on labor force characteristics, however, were essentially unchanged. In order to avoid major breaks in series, some 30,000 labor force series were adjusted back to 1970. The effect of the 1982 revisions on various data series and an explanation of the adjustment procedure used aredescribed in "Revisions in the Current Population Survey in January 1982," in the February 1982 issue ofEmployment and Earnings.The revisions did not, however, smooth out the breaks in series occurring between 1972 and 1979, and data users should make allowances for them in making certain data comparisons.

Beginning in January 1985, and again in January 1986, the CPS estimation procedures were revised due to the implementation of a new sample design (for the 1985 revision) and to reflect an explicit estimate of the number of undocumented immigrants (for the 1986 revision). The greatest impact of these revisions was on estimates of persons of Hispanic origin. Where possible these estimates were revised back to January 1980. A description of the changes and an indication of their effect on thenational estimates of labor force characteristics appear in the February 1985 and February 1986 issues ofEmployment andEarnings,respectively.

Beginning in January 1994, several changes were introduced into the CPS that effect all data comparisons with prior years. These changes include the results of a major redesign of the survey questionnaire and collection methodology, revisions to some of the labor force concepts and definitions, and the introduction of 1990 census population controls, adjusted for the estimated undercount. An explanation of the changes and their effects on the labor force data appears in "Revisions in theCurrentPopulation Survey Effective January 1994" in the February 1994 issue ofEmployment and Earnings.

Beginning 1996, 1990 census population controls, adjusted for the estimated undercount, were extended back to January 1990. A discussion of the changes and their effects on the labor force data appears in "Revisions In Household Survey DataEffective February 1996" in the March 1996 issue of Employment and Earnings.

Beginning in January 1997, the CPS reflects updated 1990 census-based population controls. The greatest impact of the new population controls was on estimates for persons of Hispanic origin. An explanation of the changes and their effects on labor force estimates appear in "Revisions in the Current Population Survey Effective January 1997" in the February 1997 issue of Employmentand Earnings.

Beginning in January 1998, the CPS reflects the introduction of new composite estimation procedures and revised 1990 census-based population controls. An explanation of the changes and their effects on labor force estimates appear in"Revisions in the Current Population Survey Effective January 1998" in the February 1998 issue ofEmployment and Earnings.

Beginning in January 1999, the CPS reflects the introduction of revised 1990 census-based population controls that incorporate newly updated information on immigration. An explanation of the changes and their effects on labor force estimates appear in "Revisions in the Current Population Survey Effective January1999" in the February 1999 issue of Employment and Earnings.

Hours and earnings-Average hourly earnings, based on establishment data, are gross earnings (i.e., earnings before payroll deductions) and include overtime premiums; they exclude irregular bonuses and value of payments in kind. Hours are those for which pay was received. Wages and salaries from the CPS consist of total monies received for work performed by an employee during the income year. It includes wages, salaries, commissions, tips, piece-rate payments, and cash bonuses earned before deductions were made for taxes, bonds, union dues, etc. Persons who worked 35 hours or more are classified as working full time.

Industry and occupational groups- Industry data derived from the CPS for 1983-91 utilize the 1980 census industrial classification developed from the 1972 SIC. CPS data from 1971 to 1982 were based on the 1970 census classification system, which was developed from the 1967 SIC. Most of the industry categories were not affected by the change in classification.

Establishments responding to the establishment survey are classified according to the Standard Industrial Classification (SIC) Manual. See text, Section 17, Business, for information about the SIC manual.

The occupational classification system used in the 1980 census and in the CPS for 1983-91, evolved from the 1980 Standard Occupational Classification (SOC) system, first introduced in 1977. Occupational categories used in the 1980 census classification system are so radically different from the 1970 census system used in the CPS through 1982, that their implementation represented a break in historical data series. In cases where data have not yet been converted to the 1980 classifications and still reflect the 1970 classifications (e.g., Table 704), comparisons between the two systems should not be made. To help users bridge the data gap, a limited set of estimates was developed for the 1972-82 period based on the new classifications. The estimates were developed by means of applying conversion factors created by double coding a 20-percent sample of CPS occupational records for 6 months during 1981-82. For further details, contact BLS.

Beginning in January 1992, the occupational and industrial classification system used in the 1990 census were introduced into the CPS. (These systems were largely based on the 1980 Standard Occupational Classification and the 1987 Standard Industrial Classification.) There were a few breaks in comparability between the 1980 and 1990 census-based systems, particularly within the "technical, sales, and administrative support" categories. The most notable changes in industry classification were the shift of several industries from "business services" to "professional services" and the splitting of some industries into smaller, more detailed categories.  A number of industry titles were changed as well, with no change in content.

Productivity-BLS publishes data on productivity as measured by output per hour (labor productivity), output per combined unit of labor and capital input (multifactor productivity), and, for manufacturing industries, output per combined unit of capital, labor, energy, materials, and purchased service inputs. Labor productivity and related indexes are published for the business sector as a whole and its major subsectors: non-farm business, manufacturing, non-financial corporations, and over 450 specific industries. Multifactor productivity and related measures are published for the private business sector and its major subsectors. Productivity indexes which take into account capital, labor, energy, materials, and service inputs are published for the 18 major industry groups which comprise the manufacturing sector, the utility services industry group, and for the following industries: cotton and synthetic broadwoven fabrics, household furniture, tire and inner tubes, footwear, steel, metal stampings, farm and garden machinery, refrigeration and heating equipment, motor vehicles, and railroad transportation. The major sector data are published in the BLS quarterly news release, Productivity and Costs and in the annual Multifactor Productivity Measures release.Industry productivity measures are published annually in the news releases Productivityand Costs, Manufacturing Industries,and Productivity and Costs, Services - Producing and Mining Industries. Detailed information on methods, limitations, and datasources appears in the BLSHandbook of Methods, BLS Bulletin 2490 (1997), Chapters 10 and 11.

Unions-As defined here, unions include traditional labor unions and employee associations similar to labor unions. Data on union membership status provided by BLS are for employed wage and salary workers and relate to their principal job. Earnings by union membership status are usual weekly earnings of full-time wage and salary workers. The information is collected through the Current Population Survey. Collective bargaining settlements data are available for bargaining situations involving 1,000 or more workers in private industry and state and local government.

Work stoppages-Work stoppages include all strikes and lockouts known to BLS which last for at least 1 full day or shift and involve 1,000 or more workers. All stoppages, whether or not authorized by a union, legal or illegal, are counted. Excluded are work slowdowns and instances where employees report to work late or leave early to attend mass meetings or mass rallies.

Seasonal adjustment-Many economic statistics reflect a regularly recurring seasonal movement which can be estimated on the basis of past experience. By eliminating that part of the change which can be ascribed to usual seasonal variation (e.g., climate or school openings and closings), it is possible to observe the cyclical and other nonseasonal movements in the series. However, in evaluating deviations from the seasonal pattern-that is, changes in a seasonally adjusted series-it is important to note that seasonal adjustment is merely an approximation based on past experience. Seasonally adjusted estimates have a broader margin of possible error than the original data on which they are based, since they are subject not only to sampling and other errors, but also are affected by the uncertainties of the adjustment process itself.

Statistical reliability-For discussion of statistical collection, estimation, sampling procedures, and measures of statistical reliability applicable to Census Bureau and BLS data, see Appendix III.