Technical Note The estimates in this release are based on annual average data 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 households that provides information on the labor force status, demographics, and other characteristics of the nation's civilian noninstitutional population age 16 and over. In response to the increased demand for statistical information about the foreign born, questions on nativity, citizenship, year of entry into the United States, and the parental nativity of respondents were added to the CPS beginning in January 1994. Prior to 1994, the primary sources of data on the foreign born were the decennial census, two CPS supplements (conducted in April 1983 and November 1989), and, to some extent, information collected by the U.S. Citizenship and Immigration Services (formerly known as the Immigration and Naturalization Service). The foreign- and native-born data for 2010 are not strictly comparable with data for 2009 and earlier years because of the introduction in January 2010 of revised population controls used in the CPS. The effect of the revised population controls on the foreign- and native-born estimates is unknown. However, the effect of the new controls on the monthly CPS estimates was to decrease the December 2009 employment level by 243,000 and the unemployment level by 5,000. The new population controls had a negligible impact on unemployment rates and other percentage estimates. More detailed information on the population adjustments and their effect on national labor force estimates are available at www.bls.gov/cps/cps10adj.pdf. 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 exact difference, or sampling error, varies depending upon the particular sample selected, and this 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. For a full discussion of the reliability of data from the CPS and information on estimating standard errors, see the Household Data section of the "Explanatory Notes and Estimates of Error" from Employment and Earnings Online at www.bls.gov/cps/eetech_methods.pdf. Concepts and definitions Foreign born. The foreign born are persons residing in the United States who were not U.S. citizens at birth. That is, they were born outside the United States or one of its outlying areas such as Puerto Rico or Guam, to parents neither whom was a U.S. citizen. The foreign- born population includes legally-admitted immigrants, refugees, temporary residents such as students and temporary workers, and undocumented immigrants. The survey data, however, do not separately identify the number of persons in these categories. Native born. The native born are persons born in the United States or one of its outlying areas such as Puerto Rico or Guam or who were born abroad of at least one parent who was a U.S. citizen. Race and ethnicity groups. In this release, the data are presented for non-Hispanic whites, blacks, and Asians and for persons of Hispanic or Latino ethnicity. These four groups are mutually exclusive but not exhaustive. Other race groups (including persons who selected more than one race category) are included in the overall totals but are not shown separately because the number of survey respondents is too small develop statistically reliable estimates. The presentation of the data on race and ethnicity in this release differs from that which appears in most analyses of CPS labor force data because persons of Hispanic or Latino ethnicity are separated from the race groups. Because persons of Hispanic or Latino ethnicity can be of any race, they are usually included in the race groups as well as shown separately in the Hispanic Latino ethnicity group. The reason for the difference in the data presentation in this release is because about half of the foreign born are of Hispanic or Latino ethnicity and they have somewhat different labor force characteristics than the non-Hispanic foreign born. Employed. Employed persons are (a) all those who, during the survey reference week, did any work at all as paid employees, worked in their own business, profession, or on their own farm, or who worked 15 hours or more as unpaid workers in a family-operated enterprise; and (b) all those who did not work but had jobs or businesses from which they were temporarily absent due to illness, bad weather, vacation, childcare problems, labor disputes, or personal reasons, whether or not they were paid for the time off and whether not they were seeking other jobs. Unemployed. The unemployed are persons who had no employment during the reference week, were available for work at that time, except for temporary illness, 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 be 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 is the number unemployed as a percent of the civilian labor force. Labor force participation rate. The labor force participation rate is the labor force as a percent of the population. Usual weekly earnings. Data represent earnings before taxes and other deductions and include any overtime pay, commissions, or tips usually received (at the main job in the case of multiple jobholders). Earnings reported on a basis other than weekly are converted to a weekly equivalent. Median earnings. The median is the amount which divides a given earnings distribution into two equal groups, one having earnings above the median and the other having earnings below the median.