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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 sur-
vey 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 pa-
rental 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 2008 are not strictly comparable with
data for 2007 and earlier years because of the introduction in January 2008 of
revised population controls used in the CPS. The effect of the revised popu-
lation 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 2007 employment level by 598,000 and the unemployment level by 40,000.
The updated controls had little or no effect on unemployment rates and other
ratios. More detailed information on the population adjustments and their effect
on national labor force estimates are available at http://www.bls.gov/cps/cps08adj.
pdf.
Information in this release will be made available to sensory impaired
individuals upon request. Voice phone: (202) 691-5200, TDD message referral
phone number: 1-800-877-8339.
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 de-
pending 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 sam-
pling 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 popu-
lation, inability to obtain information for all respondents in the sample, in-
ability 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" in Employment and Earnings Online at http://www.bls.gov/cps/eetech_
methods.pdf.
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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 of 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 to 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 in that 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 or Latino ethnicity group. The
reason for the difference in the data presentation in this release is be-
cause 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 or 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.
