Technical Note The estimates in this release are based on annual average data obtained from the Current Population Survey (CPS). The CPS, which is conducted by the U.S. Census Bureau for the Bureau of Labor Statistics (BLS), is a monthly survey of about 60,000 eligible households that provides information on the labor force status, demographics, and other characteristics of the nation's civilian noninstitutional population age 16 and over. Questions were added to the CPS in June 2008 to identify persons with a disability in the civilian noninstitutional population age 16 and older. The addition of these questions allowed the BLS to begin releasing monthly labor force data from the CPS for persons with a disability. The collection of these data is sponsored by the Department of Labor's Office of Disability Employment Policy. Information in this release will be made available to sensory-impaired individuals upon request. Voice phone: (202) 691-5200; Federal Relay Service: (800) 877-8339. Reliability of the estimates Statistics based on the CPS are subject to both sampling and nonsampling error. When a sample, rather than the entire population, is surveyed, there is a chance that the sample estimates may differ from the true population values they represent. The component of this difference that occurs because samples differ by chance is known as sampling error, and its variability is measured by the standard error of the estimate. There is about a 90-percent chance, or level of confidence, that an estimate based on a sample will differ by no more than 1.6 standard errors from the true population value because of sampling error. BLS analyses are generally conducted at the 90-percent level of confidence. The CPS data also are affected by nonsampling error. Nonsampling error can occur for many reasons, including the failure to sample a segment of the population, inability to obtain information for all respondents in the sample, inability or unwillingness of respondents to provide correct information, and errors made in the collection or processing of the data. Additional information about the reliability of data from the CPS and estimating standard errors is available at www.bls.gov/cps/documentation.htm#reliability. CPS estimates are controlled to population totals that are available by age, sex, race, and Hispanic ethnicity. These controls are developed by the Census Bureau and are based on complete population counts obtained in the decennial census. In the years between decennial censuses, they incorporate the latest information about population change (births, deaths, and net international migration). The Census Bureau introduces adjustments to the population controls for the CPS as part of its annual update of population estimates. The updated controls typically have a negligible impact on unemployment rates and other ratios. The estimates of the population of persons with a disability are not controlled to independent population totals of persons with a disability because such data are not available. Without independent population totals, sample-based estimates are more apt to vary from one time period to the next. Information about population controls is available at www.bls.gov/cps/documentation.htm#pop. Disability questions and concepts The CPS uses a set of six questions to identify persons with disabilities. In the CPS, persons are classified as having a disability if there is a response of "yes" to any of these questions. The disability questions appear in the CPS in the following format: This month we want to learn about people who have physical, mental, or emotional conditions that cause serious difficulty with their daily activities. Please answer for household members who are 15 years old or over. --Is anyone deaf or does anyone have serious difficulty hearing? --Is anyone blind or does anyone have serious difficulty seeing even when wearing glasses? --Because of a physical, mental, or emotional condition, does anyone have serious difficulty concentrating, remembering, or making decisions? --Does anyone have serious difficulty walking or climbing stairs? --Does anyone have difficulty dressing or bathing? --Because of a physical, mental, or emotional condition, does anyone have difficulty doing errands alone such as visiting a doctor's office or shopping? The CPS questions for identifying individuals with disabilities are only asked of household members who are age 15 and older. Each of the questions ask the respondent whether anyone in the household has the condition described, and if the respondent replies "yes," they are then asked to identify everyone in the household who has the condition. Labor force measures from the CPS are tabulated for persons age 16 and older. More information on the disability questions and the limitations of the CPS disability data is available on the BLS Web site at www.bls.gov/cps/cpsdisability_faq.htm. Other definitions Other definitions used in this release are described briefly below. Additional information on the concepts and methodology of the CPS is available at www.bls.gov/cps/documentation.htm. Employed. Employed persons are all those who, during the survey reference week, (a) did any work at all as paid employees; (b) worked in their own business, profession, or on their own farm; or (c) worked 15 hours or more as unpaid workers in a family member's business. Persons who were temporarily absent from their jobs because of illness, bad weather, vacation, labor dispute, or another reason also are counted as employed. Unemployed. Unemployed persons are those who had no employment during the reference week, were available for work at that time, and had made specific efforts to find employment sometime during the 4-week period ending with the reference week. Persons who were waiting to be recalled to a job from which they had been laid off need not have been looking for work to be classified as unemployed. Civilian labor force. The civilian labor force comprises all persons classified as employed or unemployed. Unemployment rate. The unemployment rate represents the number of unemployed persons as a percent of the civilian labor force. Not in the labor force. Persons not in the labor force include all those who are not classified as employed or unemployed. Information is collected on their desire for and availability to take a job at the time of the CPS interview, job search activity in the prior year, and reason for not looking in the 4-week period prior to the survey week. This group includes individuals marginally attached to the labor force, defined as persons not in the labor force who want and are available for a job and who have looked for work sometime in the past 12 months (or since the end of their last job if they held one within the past 12 months). They are not counted as unemployed because they had not actively searched for work in the prior 4 weeks. Within the marginally attached group are discouraged workerspersons who are not currently looking for work because they believe there are no jobs available or there are none for which they would qualify. The other persons marginally attached to the labor force group includes persons who want a job but had not looked for work in the past 4 weeks for reasons such as family responsibilities or transportation problems. Part time for economic reasons. Persons classified as at work part time for economic reasons, a measure sometimes referred to as involuntary part time, are those who gave an economic reason for working 1 to 34 hours during the reference week. Economic reasons include slack work or unfavorable business conditions, inability to find full-time work, and seasonal declines in demand. Those who usually work part time must also indicate that they want and are available for full-time work to be classified as part time for economic reasons. Occupation, industry, and class of worker. The occupation, industry, and class of worker classifications for the employed relate to the job held in the survey reference week. Persons with two or more jobs are classified in the job at which they worked the greatest number of hours. Persons are classified using the 2010 Census occupational and 2007 Census industry classification systems. The class-of-worker breakdown assigns workers to the following categories: Private and government wage and salary workers, self-employed workers, and unpaid family workers. Wage and salary workers receive wages, salary, commissions, tips, or pay in kind from a private employer or from a government unit. Self-employed persons are those who work for profit or fees in their own business, profession, trade, or farm. Only the unincorporated self-employed are included in the self-employed category. Self-employed persons who respond that their businesses are incorporated are included among wage and salary workers. Unpaid family workers are persons working without pay for 15 hours a week or more on a farm or in a business operated by a family member in their household.