Work Experience Technical Note
Last Modified Date: December 03, 2019
The data presented in this release were collected in the Annual Social and Economic
Supplement (ASEC) to the Current Population Survey (CPS). The CPS is a monthly sample
survey of about 60,000 eligible households, conducted by the U.S. Census Bureau for
the U.S. Bureau of Labor Statistics (BLS). Data from the CPS are used to obtain the
monthly estimates of the nation's employment and unemployment levels. The ASEC,
conducted in the months of February through April, includes questions about work
activity during the prior calendar year. For instance, data collected in 2019 refer
to the 2018 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 unemployment was about twice the number unemployed in an average
month during the year.
2018 estimates (in thousands)
Annual average of
monthly estimates 155,761 6,314
Annual supplement data 166,402 13,171
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 the supplement contains fewer questions
for categorizing respondents. In regard to unemployment in particular, the supplement
has no questions on the type of job search activity or on the respondent's availability
to work. Also, individuals can be counted as both employed and unemployed in the work
experience supplement data, whereas, for a specific monthly reference week, each person
is only counted in one category and employment activity takes precedence over job search
The data presented in this release are not strictly com-parable with data for earlier
years due to the introduction of updated population controls used in the CPS. The
population controls are updated each year in January to reflect the latest information
about population change. Additional information is available at
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
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.
A full discussion of the reliability of data from the CPS and information on estimating
standard errors is available at www.bls.gov/cps/documentation.htm#reliability.
Concepts and definitions
The principle concepts and definitions used in connection with the data in this release
are described briefly below.
Persons who worked. In the 2019 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 2018?" or "Did you do any temporary, part-time, or seasonal work even for a
few days during 2018?"
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 2018, did you spend
any time trying to find a job or on layoff?"
Work-experience unemployment rate. The number of persons unemployed at some time during
the year as a proportion of the number of persons who worked or looked for work during
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.
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.