4.42 Work History Data

The NLSY79 Work History Data provides researchers with a week-by-week longitudinal work record of each NLSY79 respondent from January 1, 1978, through the current survey date.

Beginning with the release of the 2000 data, the Work History file is incorporated into the main NLSY79 data set. Variables previously located on the separate Work History file can be identified by searching for areas of interest beginning with “Work History”. In addition, the reference numbers for work history variables begin with “W” instead of the standard “R.”

• Weekly Arrays
• Job Characteristics
• Employment Gaps
• Summary Labor Force Related Variables
• Descriptive Tables

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Weekly Arrays

Week-by-week records of the respondent’s labor force status and associated job(s), if employed, and the total number of hours worked each week at any job, if employed, are available. This information is contained in three week-by-week variable arrays:

• STATUS Array: Labor Force/Military Status Each Week Beginning January 1, 1978
• HOUR Array: Usual Hours Worked per Week at All Jobs Beginning January 1, 1978
• DUALJOB Array: Job Numbers for Respondents Who Worked at More Than One Job in Any Week Beginning January 1, 1978

Although data on only up to five jobs are released, data are collected on all jobs. Data for the extra jobs are used to construct summary *KEY* variables by the work history program. The number of jobs has exceeded ten for one case in 1991 and 1992, two cases in 1998, and one case in 2000.

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Job Characteristics

Because the work history arrays are now incorporated with the rest of the NLSY79 data, individual job characteristics variables are not duplicated as part of a work history data set. Job characteristics variables, such as dates of employment, pay, occupation, industry, and so on, that were previously included on the work history file can be located in the main file areas of interest as described in the applicable sections of this guide. These data can be identified by secondary work history areas of interest that have been assigned.

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Employment Gaps

Gaps within tenure with a specific employer are reported in association with that employer.  They occur between the start and stop dates given for an employer.  The respondent does not consider himself/herself completely disassociated from the relevant employer during these periods, although he or she was not actively working for that employer.  Specific variables for each gap include start and stop dates; the reason that the respondent was not working; the number of weeks that a respondent was unemployed (looking for work or on layoff) and/or out of the labor force (OLF or not looking for work), and; for those who were OLF at some time during a gap, the reason they were not looking for work. See the "Work Experience" section of this guide for a discussion of gaps with respect to job tenure.

Gaps between employers are gaps in a respondent’s employment during which s/he was not associated with any employer. The specific variables collected with respect to “within job gaps”(see the discussion in the "Work Experience" section on tenure with a specific employer) are also collected with respect to gaps between employers, with the exception of the reason that the respondent was not working during the gap.

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Summary Labor Force Related Variables

Variables are constructed summarizing different aspects of a respondent’s labor force activity, including total number of hours worked, weeks worked, weeks unemployed, weeks out of the labor force, and weeks in active military service. There are two sets of these variables, referring to each of two time periods—the period since the last interview and the past calendar year (see the "Labor Force Status" section of this guide). Variables are also created indicating the number of weeks since the previous interview and the percent of weeks for which a definite status cannot be determined in constructing the summary variables discussed above. See the "Work Experience" section for further notes on these variables.

Survey Instruments & Work History Construction: The work history data are constructed from information gathered in the “Military History,” “Current Labor Force Status or CPS,” Employer Supplement, and “Periods not Working” sections of the NLSY79 survey instruments. The work history program converts dates reported in these sections (start and stop dates, employment gap dates, enlistment and discharge dates) to week numbers, using January 1, 1978, as week #1. Week-by-week histories of a respondent’s labor force activity are constructed by filling in the weeks between the reported beginning and ending dates for different activities (or “inactivities”) with the appropriate code. In turn, this weekly accounting makes possible the construction of the summary variables.

Work History-Specific Documentation: Prior to the release of the 2000 data, work history variables were documented in a series of text files on the separate work history data set. In 2000, this information was moved to the Codebook Supplement. Appendix 18 in that document provides information about the logic and procedures used to create the work history arrays, as well as additional coding information for selected variables.

Data Files: The majority of the work history variables are constructed from variables found in the “Military,” “Job Information,” “Periods Not Working within Job Tenure,” “Jobs,” “CPS,” and “Between Job Gaps” areas of interest on the main data set. The resulting arrays are located in the “Work History” area of interest. The summary variables are included in the “Key Variables” area of interest.

Of particular interest to many researchers have been the PREVIOUSEMP# and TENURE variables associated with each employer. The PREVIOUSEMP# allows a respondent’s association with a given employer to be traced back through contiguous survey years. Using PREVIOUSEMP# and the appropriate stop and start dates, a TENURE variable is constructed for each job reported, which depicts total weeks of tenure with each employer across contiguous survey years. Users are encouraged to examine the work history documentation in Appendix 18 to determine if any such time-saving variable constructions exist with regard to their specific research interests. Work history data can also be easily employed in association with non-employment-related data from the NLSY79 main data files. A variety of employer characteristic variables can also be linked to the work history data items and arrays, including:

• Job benefits
• Promotions
• Ratings of job characteristics
• Activity most of survey week versus usual activity
• Overtime/time-off
• Job search activity
• Why looking/why not looking
• Employer size (in terms of employees)
• Shift worked for CPS employer
• Pregnancy leave
• Reason not working for employer (versus reason not looking for work, which is included in the Work History data set)
• Hourly wage (if first pay rate reported not hourly)
• Pay rate when first started with employer (if pay rate has changed)
• Time use on the job
• Travel/commuting time to and from work
• Job hierarchy/authority structure

The work history is a complete retrospective up to and including the respondent’s most recent date of interview. The questions in these survey sections are constructed to collect a complete history for each respondent, regardless of period of non-interview. For example, a respondent previously interviewed in 1984 and not interviewed again until 1989 will have a complete labor force history as of the 1989 interview, as information for the intervening period will be recovered in the 1989 interview. The “Work Experience” section contains a discussion of possible discrepancies or inconsistencies in these data. Researchers should be aware that, although such possibilities exist, they have not appeared to be a major factor in the quality and/or completeness of the work history record.

Data collected for jobs with full-time/long-term employers/CPS employers are similar to those collected for jobs held on a part-time/short-term basis with non-CPS employers. Although some specific information (most notably occupation, industry, class of worker, and specific modules such as the promotion questions in 1989 and 1990) is not collected for jobs reported to be part-time and/or short-term in nature, other job-specific data (including start and stop dates, reasons for leaving an employer, information on gaps, hours usually worked, and pay rates) are gathered for all jobs, regardless of their nature. Before 1988, information on rate of pay and government sponsorship of jobs was not gathered from those in part-time or short-term jobs. Before 1986, the exclusion for part-time work was 20 hours per week; for 1987 and later surveys, the exclusion for part-time work is 10 hours per week.

Many researchers focus on data for the CPS job. Those wishing to isolate CPS jobs only should take note that, while Job #1 is usually the CPS job, from 1979 to 1992, this is not always the case. The "Work Experience" section of this guide elaborates.

The information collected on reasons for employment gaps allows specific dates to be fixed for unemployed or OLF status only if a respondent was unemployed or OLF for the entire period of the gap. If the respondent was unemployed for part of the gap and OLF for the other part, the number of weeks unemployed and OLF is recorded, but the specific dates of periods for which the respondent was actively looking for work/on layoff and not looking for work are not collected. This prevents the Work History program from assigning specific week numbers to these states in the event of such a “split gap.” Instead, the number of weeks reported as unemployed is assigned to the middle of the total gap period, with the remainder of weeks at the beginning and end of the gap period being assigned an OLF status. Users examining the week-by-week status array containing labor force states should be aware that “split gaps” will appear as a series of “5” codes, followed by a series of “4” codes, followed by another series of “5” codes (5 5 5 5 5 .... 4 4 4 4 4 .... 5 5 5 5 5). Although the start and stop dates for the whole gap will be those actually reported by the respondent, the assignment of the unemployed and OLF states will not represent actual dates reported by the respondent. They represent only the number of weeks that a respondent reported having held each status, with the unemployed status being arbitrarily assigned to the middle portion of the gap.

Users should also be aware that for respondents with simultaneous active military status and civilian employment status, civilian labor force activity will take precedence over military status. For the purposes of constructing the week-by-week status array, the civilian job number will replace the military status code for weeks in which both states occur. The order of precedence for various labor force status codes is detailed in the work history documentation (see the discussion of the work history PL/I program in Appendix 18 of the Codebook Supplement); see also the “Work Experience” section in this guide.

For purposes of constructing the status array and computing the summary labor force activity variables, the work history program requires that specific week numbers be assigned on the basis of the job-specific start and stop dates. In the event that missing data occur in the job-specific start and stop dates, the program takes one of two actions. (1) If only the day in a given date is missing, the program assigns the number “15,” placing these dates in the middle of the month. This allows an approximate week number to be assigned. The possibility still exists, however, that a negative job/gap duration will result because the day is arbitrarily fixed. For example, a start date of 10/-2/90, which indicates a missing day, and a stop date of 10/6/90 would be read by the work history program as 10/15/90 and 10/6/90 respectively. Therefore, when the week numbers are assigned, the arbitrary assignment of “15” as the start day would give an erroneous impression that a job started after it stopped. The status array and computed summary variables will reflect the invalid data in the week numbers. (2) Dates missing a month and/or year cannot be estimated by the work history program and therefore have invalid missing codes for the week numbers. The status array and other computed variables cannot be calculated for activity within periods for which either or both of the dates have such missing information. These will also register invalidly missing information for any period in which specific dates and week numbers cannot be determined.

Comparison to Other NLS Cohorts: The NLSY97 Event History file contains created variables summarizing the month and year in which major life events occurred for each respondent, along with all main file data. Variables cover topics such as marital status, enrollment, employment status, and program participation. The NLSY97 Event History file presents employment status information in a format similar to the NLSY79 employment information, using a continuous week timeline. Although the NLS has collected information on labor force behavior since its inception, only partial work histories for respondents in the Original Cohorts can be constructed for certain survey years. The degree of completeness of the work history data varies by cohort and survey year. Refer to the BLS website at http://www.bls.gov/nls or the appropriate cohort’s User’s Guide for more precise information.

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Descriptive Tables

The tables below are presented to provide information on sample sizes by race and interview year for weeks worked and not worked. The actual reference period is the full calendar year immediately preceding the survey year. “Missing” means that the respondent is a noninterview for that survey year.

Table 4.42.1 Average Number of Weeks Working Per Year for Respondents
Who Provided Data in All Years from 1979 to 2004

Table 4.42.2 Number of Weeks Respondents Are Working, Not Working, and Unknown from NLSY79 2004 Work History Data