Economic News Release

Work Experience Technical Note

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Technical Note


   The data presented in this release were collected in the Annual Social
and Economic Supplement to the Current Population Survey (CPS).  The CPS is
a monthly sample survey conducted by the U.S. Census Bureau for the Bureau
of Labor Statistics.  Data from the CPS are used to obtain the monthly
estimates of the nation's employment and unemployment levels.  The supple-
ment, conducted in the months of February through April, includes questions
about work activity during the prior calendar year.  For instance, data col-
lected in 2007 refer to the 2006 calendar year.  Because the reference period
is a full year, the number of persons with some employment or unemployment
greatly exceeds the average levels for any given month, which are based on
a 1-week reference period, and the corresponding annual average of the monthly
estimates.  As shown below, for example, the number experiencing any unemploy-
ment during 2006 was about twice the number unemployed in an average month
during the year.

                                            Employed      Unemployed
   2006 estimates (in thousands)
     Annual average of
       monthly estimates                     144,427         7,001
     Annual supplement data                  156,658        14,424

   In addition, estimates from the supplement differ from those obtained
in the basic CPS because the questions used to classify workers as either
employed or unemployed are different.  More important, perhaps, is that
fewer questions by which to categorize respondents are asked in the sup-
plement.  In regard to unemployment in particular, the supplement has no
questions on the type of job search activity or on the respondent's avail-
ability to work.  Also, individuals can be counted as both employed and
unemployed in the work experience data, whereas, for a specific reference
week, each person is only counted in one category and employment activity
takes precedence over job search activity.
   Work experience data for 2006, which were collected in the 2007 Annual
Social and Economic Supplement to the CPS, are not strictly comparable with
data for 2005 and earlier years because of the introduction in January 2007
of revised population controls used in the CPS.  The effect of the revised
population controls on the work experience estimates is unknown.  However,
the effect of the new controls on the monthly CPS estimates was to increase
the December 2006 employment level by 153,000 and the unemployment level by
10,000.  For additional information, see "Adjustments to Household Survey
Population Estimates in January 2007" in the February 2007 issue of Employment
and Earnings, available on the Internet at http://www.bls.gov/cps/cps07adj.pdf.

   Information in this release will be made available to sensory impaired
individuals upon request.  Voice phone:  (202) 691-5200; TDD message referral
phone:  1-800-877-8339.

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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 on 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 "Explanatory Notes and
Estimates of Error" section of Employment and Earnings.

Concepts and definitions

   Persons who worked.  In the 2007 supplement, persons are considered to have
worked if they responded "yes" to either the question "Did you work at a job
or business at any time during 2006?" or "Did you do any temporary, part-time,
or seasonal work even for a few days during 2006?"

   Unemployed persons.  Persons who worked during the year but not in every
week are counted as unemployed if they also reported looking for work or
being on layoff from a job during the year.  Those who reported no work
activity during the year are considered unemployed if they responded "yes"
to the question "Even though you did not work in 2006, did you spend any
time trying to find a job or on layoff?"

   Labor force participants.  Persons who either worked or were unemployed
during the year.

   Usual full- and part-time employment.  These data refer to the number of
hours a worker typically works during most weeks of the year.  Workers are
classified as full time if they usually worked 35 hours or more in a week;
part-time employment refers to workers whose typical workweek was between
1 and 34 hours.

   Year-round and part-year employment.  Workers are classified as year round
if they worked 50 to 52 weeks.  Part-year employment refers to workers who
worked fewer than 50 weeks.

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