Chapter 1.
Labor Force Data Derived from the Current Population
Survey
Recent Changes to the Survey
Sample expansion
Beginning with the release of July 2001 data, labor force
estimates from the CPS reflect the expansion of the monthly CPS
sample from about 50,000 to about 60,000 eligible households.
This expansion was one part of the Census Bureaus plan to meet
the requirement of the State Childrens Health Insurance Program
(SCHIP) legislation. The SCHIP legislation requires the Census
Bureau to improve State estimates of the number of children who
live in low-income families and lack health insurance.
These estimates are obtained from the Annual Demographic
Supplement to the CPS (better known as the March income
supplement).
In September 2000, the Census Bureau began expanding the
monthly CPS sample in 31 states and the District of Columbia.
The additional 10,000 households were added to the sample over a
3-month period. BLS chose not to include the additional
households in the official labor force estimates, however, until
it had sufficient time to evaluate the estimates from the
expanded sample.
Estimates at the national level (not seasonally adjusted)
derived from the 50,000- and 60,000-household samples were
virtually the same. In any given month, the 60,000-household
sample estimates for the overall labor force participation rate
and the employment-population ratio differed by no more than 0.1
percentage point from estimates produced from the
50,000-household sample. The overall unemployment rates were
identical in both samples. (For a discussion of the effect of
the sample expansion on State estimates, see the forthcoming
update of chapter 4.)
At the national level, previously published monthly labor
force estimates for January to June 2001 were not revised,
because the differences between the two samples were minimal.
The 2001 annual averages for all labor force series, however,
were calculated using the monthly average (January-December)
from the expanded 60,000-household sample.
The 1994 redesign
A major redesign of the CPS was implemented in January 1994.
The primary objective was to improve the quality of the data
derived from the survey by introducing a new questionnaire and
modernized data collection methods. Prior to 1994, the survey
questionnaire had been virtually unchanged since 1967, at which
time changes had been introduced based on recommendations of the
Gordon Committee (Presidents Committee to Appraise Employment
and Unemployment Statistics, 1962). Additional changes were
proposed in the late 1970s based on the recommendations of
the Levitan Commission (National Commission on Employment and
Unemployment Statistics, 1979); these, in part, formed the
basis for the 1994 redesign.
The redesign of the questionnaire had four main objectives: 1)
To adopt a computer-assisted interviewing environment, 2) to
measure the official labor force concepts more precisely, 3) to
expand the amount of data available, and 4) to implement several
definitional changes.
Computerization. The new questionnaire was designed
for a computer-assisted interview, in which interviewers ask the
survey questions as they appear automatically on the screen of
their laptop computer, and then type the responses directly into
the laptop. In most cases, interviewers conduct the survey either
in person at the respondents home or by telephone from the
interviewers home. This mode of data collection is known as
computer-assisted personal interviewing (CAPI). (In addition,
about 10 percent of sample households are interviewed from
centralized telephone centers, as explained below in the section
on collection methods.)
Computer-assisted interviewing has important benefits, most
notably that it facilitates the use of a relatively complex
questionnaire that incorporates complicated skip patterns and
standardized followup questions. Additionally, certain questions
are automatically tailored to the individuals situation to make
them more understandable. The computerized questionnaire also has
several built-in editing features, including automatic checks for
internal consistency and unlikely responses. An automated
interview also permits dependent interviewing, that is, the use
of information in the current interview that was obtained in a
previous months interview. Dependent interviewing reduces
respondent and interviewer burden, while improving consistency
of the data from one month to the next. The technique is being
used to confirm the previously reported industry and occupation
of a persons job, to calculate unemployment duration, and, for
many people not in the labor force, to confirm their status as
retired or disabled.
Major questionnaire changes. While the labor force
status of most people is straightforward, some persons are more
difficult to classify correctly, especially if they are engaged
in activities that are relatively informal or intermittent. Many
of the changes to the questionnaire were made to deal with such
cases. This was accomplished by rewording and adding questions to
conform more precisely to the official definitions, making the
questions easier to understand and answer, minimizing reliance
on volunteered responses, revising response categories, and
taking advantage of the benefits of an automated interview.
Areas affected by these improvements include:
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On layoff. Persons on layoff are defined as those
who are separated from a job to which they are awaiting recall.
The old questionnaire, however, was not structured to
consistently obtain information on the expectation of recall. In
order to measure layoffs more accurately, questions were added to
determine if people reported to be on layoff did in fact have an
expectation of recallthat is, had they been given a specific
date to return to work or, at least, had they been given an
indication that they would be recalled within the next 6
months.
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Jobsearch methods. To allow interviewers to better
distinguish between active and passive methods, the response
categories for jobsearch methods were expanded and reformatted.
Also, the basic question on jobsearch methods was reworded and
followup questions were added to encourage respondents to report
all types of jobsearch activity.
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Hours at work. To improve the accuracy of these
data, the series of questions on hours worked was reordered to
incorporate a recall strategy that asks for usual hours first,
then about possible time taken off or extra hours worked during
the reference week, and finally about hours actually worked.
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Reasons for working part time. Persons who work
part time do so either for noneconomic reasons (that is, because
of personal constraints or preferences) or for economic reasons
(that is, because of business-related constraints such as slack
work or the lack of full-time opportunities). Because
respondents typically are not familiar with this distinction,
the question was reworded to provide examples of the two types
of reasons. More importantly, the measurement of working part
time involuntarily (or for economic reasons) was modified to
better reflect the concept. Starting in 1994, workers who
usually work part time and are working part time involuntarily
must want and be available for full-time work.
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Earnings. With the previous questionnaire,
respondents were asked to report their earnings as a weekly
amount, even though that may not have been the easiest way for
them to recall or report their earnings. In the new version,
respondents are asked to report earnings in the timeframe that
they find easiest, for example, hourly, weekly, biweekly,
monthly, or annual. Weekly earnings are automatically calculated
for persons who respond on a basis other than weekly.
New data and definitional changes. The questionnaire
redesign also made it possible to collect several types of data
regularly for the first time, namely:
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Multiple jobholding. Employed persons now are
asked each month whether they had more than one job. This allows
BLS to produce estimates of multiple jobholding on a monthly
basis, rather than having to derive them through special,
periodic supplements.
-
Usual hours. All employed persons are asked each
month about the hours they usually work. Previously, information
on usual hours was collected from just one-quarter of wage and
salary workers each month.
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Other definitional changes. In addition, several labor
force definitions were modified. The most important definitional
changes concerned discouraged workers. The Levitan Commission
had criticized the former definition because it was based on a
subjective desire for work and on somewhat arbitrary assumptions
about an individuals availability to take a job. As a result of
the redesign, two requirements were added: For persons to qualify
as discouraged, they must have engaged in some jobsearch within
the past year (or since they last worked, if they worked within
the past year), and they must be currently available to take
a job. (Formerly, availability was inferred from responses to
other questions; now, there is a direct question.) Also,
beginning in January 1994, questions on this subject are asked
of the full CPS sample, permitting estimates of the number of
discouraged workers to be published monthly
(rather than quarterly).
Another important definitional change concerned unemployed
persons who were not working just before their jobsearch
commenced, that is, new entrants or reentrants to the labor
force. Prior to 1994, new entrants were defined as jobseekers
who had never worked at a full-time job lasting 2 weeks or
longer; reentrants were defined as jobseekers who had held a
full-time job for at least 2 weeks and then had spent some time
out of the labor force prior to their most recent period of
jobsearch. These definitions were modified to encompass any
type of job, not just a full-time job of at least 2 weeks
duration. Thus, new entrants now are defined as jobseekers
who have never worked at all, and reentrants are jobseekers
who have worked before, but not immediately prior to their
jobsearch.
Next: Changes Introduced in 2003
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