Economic News Release

Number of Jobs Held, Labor Market Activity, and Earnings Growth Among the Youngest Baby Boomers: Results from a Longitudinal Survey Technical Note

Technical Note


   The estimates in this release were obtained using data from the first 24 
rounds of the National Longitudinal Survey of Youth 1979 (NLSY79). This sur-
vey is conducted by the National Opinion Research Center at the University of 
Chicago and the Center for Human Resource Research at The Ohio State University 
under the direction and sponsorship of the U.S. Department of Labor’s 
Bureau of Labor Statistics.
   
Sample
   
   The NLSY79 is a nationally representative sample of 12,686 young men and 
women who were 14 to 22 years of age when first surveyed in 1979. This sur-
vey sample was initially composed of three subsamples:
  
   --A cross-sectional sample of 6,111 youths that was designed to represent 
     the noninstitutionalized, civilian population of young people living in 
     the U.S. in 1979 and born between Jan. 1, 1957, and Dec. 31, 1964.

   --A supplemental sample of 5,295 youths designed to oversample noninsti-
     tutionalized, civilian black, Hispanic or Latino, and economically dis-
     advantaged nonblack, non-Hispanic youths living in the U.S. in 1979 and 
     born between Jan. 1, 1957, and Dec. 31, 1964.
  
   --A military sample of 1,280 youths born between Jan. 1, 1957, and Dec. 31, 
     1961, and enlisted in the Army, Air Force, Navy, or Marine Corps as of 
     September 30, 1978.

   In 1985, the military sample was discontinued, and, in 1991, the economic-
ally disadvantaged nonblack, non-Hispanic youths were dropped from the sup-
plemental sample. As a result, the NLSY79 sample now includes 9,964 individ-
uals from the cross-sectional sample and the black and Hispanic 
supplemental samples. (This sample size is not adjusted for sample members 
who have died.)
  
  Individuals were surveyed annually from 1979 to 1994 and biennially since 
1994. In 2010-11, 7,565 individuals responded to the survey, for a retention 
rate of 76 percent. Only these individuals are included in the estimates in 
this release. All results are weighted using the 2010-11 survey weights that 
correct for the oversampling, interview nonresponse, and permanent attrition 
from the survey. When weighted, the estimates represent all persons born in 
the years 1957 to 1964 and living in the U.S. when the survey began in 1979. 
Not represented by the survey are U.S. immigrants who were born from 1957 
to 1964 and moved to the U.S. after 1979.
   
Work history data
   
   The total number of jobs that people hold during their work life is an 
easy concept to understand but a difficult one to measure. Reliable esti-
mates require a survey that interviews the same people over the course of
their entire work life and also keeps track of all the jobs they ever held. 
The NLSY79 tracks the number of jobs that people have held, but the re-
spondents in this survey are still in their prime working years, ages 45 to 53 
in 2010-11, and have many years of work life ahead of them. As the cohort 
continues to age, however, more complete information will become available.
  
  A unique feature of the NLSY79 is that it collects the beginning and end-
ing dates of all jobs held by a respondent so that a longitudinal history 
can be constructed of each respondent’s work experiences. The NLSY79 work 
history data provide a week-by-week work record of each respondent from 
Jan. 1, 1978, through the most recent survey date. These data contain in-
formation on the respondent’s labor force status each week, the usual hours 
worked per week at all jobs, and earnings for all jobs. If a respondent 
worked at more than one job in any week, hours and earnings are obtained 
for additional jobs. When a respondent who missed one or more consecutive 
survey rounds is interviewed again, he is asked to provide information 
about all time since the last interview.

Interaction between time and age in a longitudinal survey
  
   Because the NLSY79 is a longitudinal survey, meaning the same people
are surveyed over time, the ages of the respondents change with each sur-
vey round. It is important to keep in mind this inherent link between the 
calendar years and the ages of the respondents. For example, table 5 re-
ports earnings growth from age 25 to age 29. The youngest respondents in 
the sample (birth year 1964) were these ages during 1989-93, whereas the 
oldest respondents (birth year 1957) were these ages during 1982-86.

   Although participants in the NLSY79 were ages 45 to 53 during the 2010-
11 interviews, this release covers only the period while the respondents 
were ages 18 to 46. The reason for not including older ages is that the 
sample sizes were still too small to provide statistically reliable esti-
mates for age groups older than 46. As the NLSY79 continues to be adminis-
tered and the respondents age, subsequent rounds of the survey will enable 
analyses to be conducted for older age groups.

   As with age, the educational attainment of individuals may change from 
year to year. In the tables and analysis presented in this report, educa-
tional attainment is defined as of the 2010-11 survey. This definition is 
used even when data on age and educational attainment are presented together. 
For example, table 1 reports the number of jobs held during different age 
categories. Suppose that a respondent had completed a bachelor’s degree at 
age 30. That respondent would be included in the "Bachelor’s degree or more"
educational category in all age categories shown on the table, even
though he or she did not have a bachelor’s degree at any point from 
age 18 to age 29.

Definitions

   Job. A job is defined as an uninterrupted period of work with a particu-
lar employer. Jobs are therefore employer-based, not position-based. If a 
respondent indicates that he or she left a job but in a subsequent survey 
returned to the same job, it is counted as a new job. For example, if an 
individual worked in a retail establishment during the summer, quit at the 
end of summer to return to school, and then resumed working for the same 
employer the following spring, this sequence would count as two jobs, ra-
ther than one. For self-employed workers, each "new" job is defined by the 
individuals themselves.
  
   Unemployment. If respondents indicate a gap between employers, they
are asked how many of those weeks they spent searching for employment or
on layoff. For that number of weeks, they are considered unemployed. For
the remaining weeks, they are coded as not in the labor force. No probing 
for intensity of job search is done.
   
   Usual earnings. Respondents can report earnings over any time frame
(hour, day, week, month, year). For those who do not report an hourly
wage, one is constructed using usual hours worked over that time frame.
Wages greater than $100 per hour and less than $1 per hour (in January 1979 
dollars, 100=283.70 in December 2010 dollars) were not included in the 
analysis of earnings growth because the reported earnings levels were almost 
certainly in error. For the same reason, individuals who had inflation-adjusted 
earnings growth greater than 100 percent were not included in the analysis. 
These exclusions from the analysis affected 40 respondents.
   
   Race and ethnicity groups. In this release, the findings are reported
for non-Hispanic whites, non-Hispanic blacks, and Hispanics or Latinos.
These three groups are mutually exclusive but not exhaustive. Other race
groups, which are included in the overall totals, are not shown separately 
because their representation in the survey sample is not sufficiently 
large to provide statistically reliable estimates. In other BLS publica-
tions, estimates usually are published for whites, blacks, and Hispanics 
or Latinos, but these groups are not mutually exclusive. The term "His-
panic or Latino" is considered to be an ethnicity group, and Hispanics 
or Latinos can be of any race. Most other BLS publications include Hispan-
ics or Latinos in the white and black race groups in addition to the His-
panic or Latino ethnicity group.

   Information in this release will be made available to sensory impaired 
individuals upon request. Voice phone:  (202) 691-5200; Federal Relay Ser-
vice:  (800) 877-8339.



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Last Modified Date: July 25, 2012
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