NLSY79 Appendix 18: Work History Data

National Longitudinal Survey of Youth - 1979 Cohort

NLSY79 Appendix 18: Work History Data

  • NLSY79 WEEK NUMBERS AND CORRESPONDING DATES (Separate Excel File). The Continuous Week Crosswalk contains the start date for each week (Sunday) from January 1, 1978, through December 31, 2015, and the week numbers assigned to that week in the construction of the work history data file. These week numbers do not match the week numbers printed on the employment calendar included with the survey instrument materials. Week numbers in the work history programs are assigned based upon actual dates collected during the course of the interview. The variable names for the week-by-week arrays (status, hours, dual jobs) incorporate the specific year and number of the week within the specific year. For example, the 10th week in 1989 in the status array is called STAT8910. These names do not correspond to the strictly consecutive week numbers from 1-1984 listed in the Excel spreadsheet. The spreadsheet also contains the week numbers for each calendar year so that users will have a crosswalk for both calendar-year and continuous week numbers.

DESCRIPTION OF THE 1979-2014 NLSY79 WORK HISTORY PROGRAM

This document provides a general explanation of the procedures and logic of the work history programming and variables. The original PL/I programming was used to establish and maintain the structure and data from survey years 1979 to 1994. Therefore, the following discussion heavily references these programs.  The series of SQL programs currently in use were converted directly from the PL/I code for the 1996 release.

The original PL/I work history program was written to create key work variables like "Number of Weeks Worked since Date of Last Interview," "Number of Weeks Worked in Last Calendar Year," etc. These key variables use all recorded jobs for each respondent (up to 10 jobs). The WEEKLY LABOR STATUS, HOURS WORKED, and DUAL JOBS arrays also were created with data from up to 10 jobs for each respondent. However, only 1% of all respondents have more than 5 jobs in any given survey year, resulting in valid missing data for jobs 6 through 10 for 99% of the sample. In order to reduce the total number of variables, public data files contain the specific employer variables for only 5 jobs for each respondent.

The purpose of the WEEKLY LABOR STATUS, HOURS WORKED and DUAL JOBS arrays is to create a longitudinal work history record for each respondent through the 2014 (round 26) interview date. Because each year's survey collects information on jobs held and periods not working since the date of the last interview, it is possible to construct a continuous, week-by-week record for each respondent.

There are a few exceptions, however. In the 1979 and 1980 surveys, job information was collected only for respondents age 16 and older at the date of the interview. Additionally, the 1979 survey data contain the most cases with inconsistent or invalid employment-related data of any survey year, resulting in a greater proportion of missing gaps in the work history record. For example, in 1979 there are 86 cases that have job dates that exceed the interview date; in 1980, there are 11 cases that have job dates that exceed the interview date; in 1981 there are none.

Users should also note that 1,079 members of the military sample were dropped as of the 1985 survey. In 1991, all members of the economically disadvantaged non-black/non-Hispanic oversample were dropped as well. More information on these sample types is available in the Retention and Reasons for Noninterview section.

Description of the 1979-94 PL/1 Program

The following is an abbreviated step-by-step description of the original 1979-1994 PL/I programming. In 1996, the PL/I program was converted to SQL code in a series of programs that replicate the PL/I program and functions. See the "Changes between the 1979-94 and the 1979-96 Work History Data" paragraphs in this section for more information. 

  1. All of the variables used in the program are declared and most are included in the PL/I structure called VARIABLES.
  2. The variables common to all respondents, like ID, SAMPLE_ID, etc. are assigned values. The week-by-week arrays are initialized to zero and all of the variables included in the WORK_HISTORY part of the structure are initialized to -4.
  3. For each interview year, procedures (VARIABLES1979, VARIABLES1980, etc.) that assign the variables for each survey year are called if the respondent was interviewed. Start and stop dates for jobs and periods not working are sent to the WEEK procedure, where the valid month, day and year variables are converted to a week number, with week 1 being January 1, 1978. If the respondent was not interviewed, then all WORK_HISTORY variables for that survey year are set to -5.
  4. After all VARIABLES19XX are assigned, the procedure CALC is called to evaluate the various start and stop dates, to assign codes, and to create the job number for all of the jobs for each interview year. Within CALC, the procedure FILL is called to fill in the codes that are assigned to the WEEKLY LABOR STATUS and DUAL JOBS arrays and to calculate the hours worked during each week that are loaded into the HOURS WORKED array.
  5. Finally, the procedure SUMMER is called to calculate and sum the key work history variables.

CALC Procedure (in original PL/1 program)

This procedure processes all jobs for each survey year, beginning with the first job. CALC starts by calculating each year the number of jobs since the date of the last interview, assigning a job number, and calculating the hourly wage for each job. If the respondent had the job at the date of the last interview, the start date becomes the date of the last interview, which is then "ceiled" or rounded up using the "ceil" function. Next, if the respondent is currently working at the job, it assigns the interview date, which is "floored" or rounded down using the "floor" function, as the stop date. (All dates at this point have been converted to week numbers in the WEEK procedure.)

If the start and stop dates of the job are valid and do not coincide with an interview date, the start and stop dates are "ceiled." The number of weeks tenure on the job is calculated by subtracting the start week from the stop week of the job. FILL is then called to fill in the week arrays for the particular job. The start and stop weeks of the job, the job number, and the number of hours usually worked per week (HOURSWEEK) at the job are sent to the FILL procedure.

If the job had any periods not working associated with it, then up to four periods not working for the employer are processed. If the start and stop dates for the periods not working are valid, a code is assigned indicating whether the respondent was out of the labor force (OLF) or unemployed for the period. If the respondent is OLF the whole period, a code of 4 is assigned. If the period not working is divided between OLF and unemployed, a temporary code of 9 is assigned and the number of weeks unemployed is determined. If the start and stop dates of the period are valid, but the labor force status cannot be determined, a code of 2 is assigned.

The period start and stop dates, CODE, and HOURSWEEK are sent to FILL. If the period dates are invalid, a code of 3 is assigned and start and stop dates of the job are passed to FILL, along with HOURSWEEK. This is only done for the first period not working for the first employer this week.

Next, tenure at the job is again calculated, this time in terms of total weeks on the job instead of just since the date of the last interview. First, a determination is made to see if the employer is the same employer a respondent reported at the time of the previous interview. If there is a previous employer number and the tenure for that previous employer is valid, then the tenure for the job from the previous interview is added to the tenure for the job being processed. Only tenure with an employer that is reported during contiguous survey years can be calculated over the total time spent with an employer. For example, consider a respondent who was interviewed in 1981, 1982 and 1983 surveys. Now suppose the respondent reported having worked for the Department of Labor at the time of the 1981 survey and left and then began working for that same employer again by the time of the 1983 survey. Because the employer numbers are only followed between contiguous interviews, there is no way to calculate total tenure with the Labor Department since the respondent did not report that employer during the 1982 survey. Only employers from the previous year's survey are compared with employers reported in the current year's survey.

Finally, CALC evaluates up to six periods not working or in the military between jobs. For each of the periods not working, the same logic used for the periods not working on a job is used for the periods between jobs.

 

User Notes

1. If the start and stop dates for a job are invalid, then that job has no dates that can be sent to FILL. As a result, there is no record of that job in the WEEKLY LABOR STATUS array and no indication that the job is missing. In 1979, there were 1190 cases with any invalid start or stop dates (i.e., at least one week is unaccounted for - WEEKLY LABOR STATUS=0); in 1980, there were 942 cases; in 1981, there were 254; and in each of the following survey years, there were fewer than 200 cases.

2. A job held in any day of a week is counted as a job for the whole week. This is achieved by "flooring" start dates and "ceiling" stop job dates to integer week values. There is one exception previously mentioned--stop dates for jobs held at the interview date are floored. This is done to avoid double counting across interview years.

3. Start and stop dates for periods not working either within tenure with a job or between jobs are "ceiled" in FILL.

4. The HOURS WORKED array is set to -3 if any job in the week has an invalid value for HOURSWEEK. Between 1979 and 1992, the maximum number of hours for any given week is 96. Beginning in 1993, the maximum number of hours for a given week can be reported up to 168 hours (the total number of hours possible in a single week).

FILL Procedure

The FILL procedure takes the start and stop dates that have been converted to week number values and fills in values for the WEEKLY LABOR STATUS, HOURS WORKED and DUAL JOBS arrays for each week between stopping and starting dates that are passed to it.

In FILL, the WEELY LABOR STATUS array is loaded with either a survey year job number or a code signifying that there was not one civilian job that week (a code of 0, 2, 3, 4, 5, or 7). The DUAL JOBS array is loaded with a survey year job number(s) if more than a civilian job is held that week; otherwise it is assigned a value of 0. The HOURS WORKED array is loaded with the number of hours worked on all jobs held that week, up to a maximum of 96 through 1992, and a maximum of 168 in subsequent years.

FILL is called from the CALC procedure for all start and stop dates except for military start and stop dates. Military start and stop dates are determined in the VARIABLES procedures for each year, and FILL is called from those procedures to fill in a code of 7 in the WEEKLY LABOR STATUS array for active military service.

Initially, FILL checks for valid start and stop dates. If the dates are valid, then FILL takes one of three paths. The first path is to evaluate the WEEKLY LABOR STATUS array for that week to see (1) if it contains a job number, (2) if the code passed from CALC is a job number, and (3) if the previous employer number for the job is different from the job number in the WEEKLY LABOR STATUS array. If all of these statements are true, then FILL determines that the job is not a duplication of the job that exists in the WEEKLY LABOR STATUS array for that week.

Next, FILL looks at the DUAL JOBS array to see if there is a job number in DUAL JOBS. If DUAL JOBS already has a job number(s), then the current job number is compared to the job number(s) in DUAL JOBS. If the job number does not exist in DUAL JOBS, then the HOURSWEEK for that job is added to the number of hours for that week for the HOURS WORKED array and the job number is added to DUAL JOBS. If the job is a duplicate job, then nothing is done to the arrays.

The second path is taken if there is no dual job and if the week dates are associated with a job or if there is not job number in the WEEKLY LABOR STATUS array. If this is the case, FILL tests for two conditions. The first condition is met if COD is 9. (A code of 9 means that the respondent had a period not working that was part OLF and part unemployed.) If COD equals 9, then the HOURSWEEK are subtracted from the hours in the HOURS WORKED array, because the respondent is not working at the job. The number of weeks unemployed (code of 4) is arbitrarily assigned to the middle portion of the weeks not working, and the rest of the period is determined to be OLF (code of 5).

The second condition in the second path tests to see if the value in the WEEKLY LABOR STATUS array is not a code of 4; if COD is a job number then the job number is placed into WEEKLY LABOR STATUS. If there are hours for the week and if the respondent was not working for the employer during this week, then the hours for the week are set to zero if the HOURS WORKED array is greater than zero. Otherwise, HOURS WORKED receives whatever value is in HOURSWEEK.

The third path FILL evaluates is if the week falls in a period not working and if there is a dual job. Then, the job number is deleted from the DUAL JOBS array and HOURSWEEK for the job are subtracted from the HOURS WORKED array.

Finally, if there are more than four dual jobs in the DUAL JOBS array then no other job numbers are added to DUAL JOBS because the array for each week is limited to four dual job variables.

 

User Notes

A few last notes about FILL:

1. Civilian work takes precedence over any other activity. If the respondent has a civilian job while in the military, then the civilian job code replaces the military code in the WEEKLY LABOR STATUS array.

2. The order of precedence in the construction of the WEEKLY LABOR STATUS array after a civilian job is as follows:

  1. a code of 3, associated with an employer but periods not working with employer are missing; if any period not working is missing, then the entire period of the job is assigned a 3. In 1979, there are 274 cases with invalid period dates, and in each of the following survey years, there are fewer than 60 cases
  2. a code of 4, unemployed
  3. a code of 5, OLF
  4. a code of 2, period not working with employer, but OLF vs unemployed status is unknown
  5. a code of 7, active military service
  6. a code of 0, no information is reported to account for the week

3. About 32 cases have a week in which JOB # 1 from a survey week first appears in the DUAL JOBS array rather than the WEEKLY LABOR STATUS array. This occurs when (1) there is a discrepancy between the date of the previous interview date as it appears on the info sheet that the interviewer uses at the time of the interview and the interview date recorded at the previous interview or (2) the starting date and ending date for a job across interview years are the same due primarily to the way the dates are floored and ceiled. In all these cases, an erroneous entry appears in the DUAL JOBS array for that given week.

Changes between the 1979-86 and the 1979-87 Work History Data File

In 1987, a few changes were made to the program that created the work history data. These changes from the 1986 program affected the created labor force participation key variables, the WEEKLY LABOR STATUS array, and the HOURS WORKED array.

The following is a detailed discussion of the changes in the code that were made and the effects of those changes on the key variables and the week-by-week arrays:

  1. In the CALC PROC, the stop dates for all jobs and all periods not working were set to the interview date if the dates were greater than zero and if they were greater than the interview date. These changes resulted in an increased number of weeks unaccounted for in calculating weeks not working and in changes in the number of weeks unemployed and out of the labor force across all of the key variables for each survey year. Most of the changes were a difference of one week or a change to an invalid value.
  2. In the FILL PROC when hours were subtracted from the weekly HOURS WORKED array, a check was made to determine if the subtraction resulted in a value greater than or equal to zero. If it did not, the value in the HOURS WORKED array for that week was set to zero. If there was no dual job for that week, then the value in the HOURS WORKED array for that week was set to zero; previously, a subtraction was performed.
  3. Before these changes, some cases had negative hours (not including missing value codes) in some of the weeks in the HOURS WORKED array. Now, all of the values in the HOURS WORKED array are positive except for the standard missing values. These changes resulted in an overall decrease in the number of hours reported in a given week and in the number of hours calculated for the last calendar year and since the date of the last interview for those cases that were affected.

Note: To view a table listing the key variables for each year that had a change in values and the number of cases that had a change in the calculation of that key variable between the 1979-87 work history creations and the previous years, click here.

Changes between the 1979-87 and the 1979-88 Work History Data File

Most changes made to the work history program between the 1979-87 and 1979-88 releases did not affect the content of the variables themselves. Some changes were made to simplify the reading and use of the program in the future. Format changes were also made to allow for larger variable lengths. Because 1988 is the 10th year of the NLSY79, variables such as a job number, which provided only one space for the survey year, were expanded. The DUAL JOB array was no longer concatenated. Instead, four variables are created for each week in the array, allowing (as before) for up to four dual jobs per week.

Substantive changes are not major and are a function of changes in the questionnaire:

  • HOURSWEEK in 1988 also includes additional hours worked at home if any are reported. The 1988 questionnaire asked respondents separately about hours worked at home for a job. If any hours worked at home were reported, respondents were asked if their total hours worked per week included those hours worked at home. If not, the total hours worked per week and the hours worked at home were added together to get a total number of hours worked per week anywhere for a job.

Changes between the 1979-88 and the 1979-89 Work History Data File

A new set of variables was created in the 1979-89 work history program. These additions did not affect the content or substance of already existing variables.

  • A set of JOBSEVER variables was created from 1979-1989. These variables provide a cumulative count of the number of different jobs that have ever been reported by a respondent up to the date of interview for the survey year. Users should note that, as with calculations for the TENURE variables discussed earlier in this program description, employers can only be traced through contiguous years. In non-contiguous years, the number of jobs reported may be slightly inflated in some cases.

Some data changes were made in existing variables as well. Two of these reflect corrections that have been made in the calculations for 1987 and 1988 variables.

  1. The 1987-88 TENURE variables created by the 1979-87 and 1979-88 work history programs were in error. An error in the program statements which calculate this variable resulted in large numbers of respondents with valid values receiving -3 values instead. This error was corrected and the changes have been incorporated in subsequent releases.
  2. Beginning with the 1979-88 data release, the HOURSWEEK variable was created to include additional hours worked at home on a job, if reported. Although this was true for employers #6-10, the necessary programming changes for employers #1-5 were inadvertently omitted from the program. Therefore, employers #1-5 were calculated as they have been in previous work history programs, based upon one question without qualification for any additional hours worked at home. The omission was corrected.
  3. In 1988, 116 cases reported a 3rd within-job gap for at least one job. The information for these gaps was erroneously included as information for a 4th within-job gap. The 3rd within-job gaps for these cases would have been missing. This was corrected for the 1979-89 release. Additionally, information on a 4th within-job gap for at least one job was included for 18 cases.

Changes between the 1979-89 and the 1979-90 Work History Data File

A minor modification was made to the procedure which calculates the Hourly Rate of Pay (HRP#) from PAYRATE and TIMEUNIT). Starting in 1990, any PAYRATE with a value of 9999995 is set to -4 by the HRP procedure. This 9999995 value indicates a case for which the dollars and cents PAYRATE exceeded $100,000.00.

Some data updates were made to existing variables as well.

  1. Specific job information for 70 cases was edited, for one or more jobs, due to improper identification of CPS jobs in the Employer Supplements.
  2. Corrections were made to 23 cases for 1988 PAYRATES and/or 1988-89 HOURLYWAGES. These cases exceeded $100,000.00 and should have been assigned the 9999995 value. While some contained that value, some retained an erroneous dollars and cents value in PAYRATE. In either case, the HOURLYWAGEs were calculated based upon an incorrect PAYRATE figure. The above-mentioned adjustment to HRP procedure will prevent the calculation of HOURLYWAGE figures from the truncated 9999995 value in the future.

Changes between the 1979-91 and the 1979-92 Work History Data File

A change has been made to the structure of the 1979-92 work history data file on magnetic tape only. Due to the volume of the current work history data file, the data were split into two records. The first record contains the data for the STATUS, HOURS and DUALJOBS arrays. The second contains the remainder of the data, pertaining to specific job characteristics, gaps in employment and summary labor force activity variables. Those wishing to use only job specific variables can now do so without being required to process information for an entire case to do so. Those wishing to incorporate the arrays in analysis can access them in a separate record. Tape users should refer to the record layout and format table provided in this package of documentation for details on the exact location of each variable. This change does not affect the content or substance of already existing variables.

A correction was made to an existing set of variables as well. Users have already been notified of the inadvertent omission of hourly rates of pay for those respondent reporting earnings on a semi-monthly basis in the 1990 and 1991 main NLSY79 and work history data files, and in the Winter 1993 (No. 74) issue of NLSUPDATE. These cases have been corrected in the 1979-92 version of the work history data file.

Changes between the 1979-92 and the 1979-93 Work History Data

Beginning with the 1979-93 release, the formats for the PAYRATE variables have been extended to 8 characters to accommodate values up to 99999999 ($999999.99). Previously, these cases containing these variables had been assigned a PAYRATE value of 9999995 and set to -4 in the HRP procedure, which creates the HOURLYWAGE variables. Valid PAYRATE and HOURLYWAGE values are now present in these cases.

Changes between the 1979-93 and the 1979-94 Work History Data

The recall experiment (an experiment to test the recall of respondents over a two year period) was conducted with over 850 randomly selected respondents during the 1994 interview. For this experiment, respondents were treated as if the 1993 interview never took place; the interview was conducted as if the 1992 interview was the most recent. Because data from 1993 were already incorporated into the work history data, programmers sought to keep redundant data from the 1994 interview for the "recall" cases from overwriting the already incorporated 1993 data. Efforts were made to eliminate the overlap between the information reported in 1993 and 1994 for those cases, and to keep only the information from the 1994 interview that covered the period since the 1993 interview. However, there were isolated circumstances in which this was not possible. These relate to the assignment of "OLF" versus "unemployed" labor force status during periods not working which contain both types of statuses (see earlier discussion in this document). While it is possible to determine which part of a period not working occurred since the 1993 interview, it is not possible to make the same determination for "OLF" versus "unemployed" status during those periods. Therefore, it is likely that in some cases these statuses would not have been assigned correctly to certain periods not working. See Appendix 16 for further details on the recall experiment.

Changes between the 1979-94 and the 1979-96 Work History Data

Through survey year 1994, the work history data was created by running PL/I programs on an IBM mainframe. In 1996, the volume of the work history data dictated a change to a more efficient method of production. To create the 1979-96 data, the PL/I program was converted to a series of programs SQL code. Relevant variables from the main NLSY79 data were loaded into a relational data base, from which the work history data was generated. The SQL code that generated the data replicates the PL/I program, both in substance and function.

For respondents with missing interviews between the last interview and 1996, the WEEKLY LABOR STATUS, HOURS WORKED and DUAL JOB arrays were updated by the SQL program in the same manner as in past years with the PL/I programs.

Although the SQL programs are not included in this appendix, a separate addendum contains the PL/I programs from past years (see Work History PL/1 Programs). A list of the main NLSY79 variables used in the creation of the 1979-96 work history data set is accessible at the end of this appendix.

Changes between the 1979-96 and the 1979-98 Work History Data

Windows-based extraction software accompanied the 1979-98 separate Work History data release for the first time.

The TENURE variable for job #2, reported in 1980, was found to be in error on the 1979-96 work history release only. This variable was replaced with the correct data on the 1979-98 work history release.

Changes between the 1979-98 and the 1979-2000 Work History Data File

The 1979-2000 (round 19) combined public data release, marked the first time that the work history data was released in combination with the main NLSY79 data. Data items formerly available only in a separate work history data release, including the week-by-week arrays, were made available in a series of new areas of interest in the public release data set, using the same extraction software as the main NLSY79 data. This eliminated the need for multiple extracts and merging of data from different data sets, as well as the duplication of some information specific to individual jobs and respondents between data files.

The following areas of interest contain variables generated by the Work History programs that were formerly available only on the separate Work History release.

  • WORK HISTORY -- CALENDAR YEAR
  • WORK HISTORY -- DUAL JOBS
  • WORK HISTORY -- GAPS BETWEEN JOBS
  • WORK HISTORY --HISTORY
  • WORK HISTORY -- HOURS WORKED
  • WORK HISTORY -- JOBS
  • WORK HISTORY -- MILITARY
  • WORK HISTORY -- SINCE LAST INTERVIEW
  • WORK HISTORY -- WEEKLY LABOR STATUS

Areas of interest beginning with 'WORK HISTORY -- MAIN' contain main data survey variables that are either:

  • components used in the Work History programs or;
  • survey variables that were also included in the separate Work History data file before the 1979-2000 release.

Changes between the 1979-2000 and the 1979-2002 Work History Data

The 1979-2002 (round 20) Employer Supplements underwent some significant revisions to better accommodate respondents reporting self-employed and non-traditional (temporary, contracting, on-call, etc.) types of employment situations, as well as teaching occupations. Many adjustments involved asking comparable or consistent questions with wording more appropriate to the type of employment being reported. These additional questions have been incorporated wherever necessary in the construction of the Work History data to produce variables consistent with those produced historically. Relevant question names are noted in the discussions below.

The 2000 Census Industry and Occupation Classifications were used to code the 2002 NLSY79 data. Prior to survey year 2002, industry and occupation data were coded using the 1970 codes, with 1980 codes being assigned to the current/most recent job for the respondent only.

DESCRIPTION AND CODES FOR VARIABLES IN 1979-2014 NLSY79 WORK HISTORY DATA

Below are discussions of three types of variables:

  • the weekly arrays created by the Work History programs 
  • other items produced by the Work History programs 
  • variables that are either used in the Work History programs, or are basic, commonly used job-specific survey items that were duplicated on the separate Work History data sets prior to the 1979-2000 release.  When the Work History data became part of the general public 1979-2000 release, these variables were assigned to areas of interest titled WORK HISTORY --MAIN -- JOB INFORMATION [YEAR], to make it easier for historical data users to recreate the separate Work History data files they may have been working with up to that point.

Variable coding information, as well as formulas for combining job-specific characteristics from several sources, are included where relevant.

Work history weekly array variables

The foundation of the work history data is the set of week-by-week arrays depicting labor force status, total number of hours, and dual job holdings if any, for each week since January 1, 1978. These array variables are found in three areas of interest in the NLSY79 public release. The construction and coding for each of the three arrays are described below, listed by their area of interest.

Area of interest: WORK HISTORY-WEEKLY LABOR STATUS

The WEEKLY LABOR STATUS array is the work history week array. Each variable corresponds to a week relative to 1/1/78.[1] There are 1984 variables in the 1979-2014 WEEKLY LABOR STATUS array--one for each of the 1984 weeks from 1/1/78 to 12/29/2013.[1] [4] There are no missing data codes, and the codes that are in the array are as follows:

  0= no information reported to account for week.
  2= not working (unemployment vs. out of the labor force cannot be determined.)
  3= associated with an employer but the periods not working for the employer are missing. If all of the time with the employer cannot be accounted for, a 3 is loaded into the STATUS array instead of a job code.
  4= unemployed. If a respondent is not working and part of the time is spent looking for work or on layoff, the exact weeks spent looking for work is unknown. As a result, the number of weeks spent looking is assigned to the middle part of the period not working.
  5= out of the labor force.
  7= active military service. If a respondent has a civilian job while in active military service, the civilian job code is loaded into the array instead of a code of 7.
  >100= worked. The code represents the appropriate work history year multiplied by 100 plus the job number for that employer in that year. For example, 102=year 1, job 2; 305=year 3, job 5. This allows one to associate any characteristic for a job with that week. If a respondent has more than one job at the same time, the job number that is loaded into the array is determined by the starting date of the job with the lowest job number, not by any particular characteristics of the job such as the number of hours worked at the job. The year in the job code is the year in which the job is reported. Jobs held in year 2, but reported in year 10 would be assigned job numbers beginning with 1001 instead of 201.

 

User Notes

In some cases, a respondent reports a period not working that is part OLF and part unemployed. In these cases, a week-specific distinction between OLF and unemployed cannot be made. Users should refer to the Work History Program Description in this appendix for a discussion of how OLF and unemployed codes are assigned to the WEEKLY LABOR STATUS array in the event that such a period occurs.

Area of interest: WORK HISTORY-HOURS WORKED

The HOURS WORKED array contains the usual hours worked per week at all jobs. There are 1984 variables in the 1979-2014 HOURS WORKED array--one for each of the 1984 weeks from 1/1/78 to 12/27/2015.[2] [5] The codes are as follows:

  0 no hours worked or interview does not cover array week
  1-95 = usual hours worked per week
  96 = 96 or more hours per week
  -5 = noninterview
  -4 = valid skip
  -3 = invalid skip
  -2 = don't know
  -1 = refusal

 

User Notes

Beginning in 1993, the first all-CAPI survey year, the maximum hours allowed per week is 168.

Area of interest: WORK HISTORY-DUAL JOBS

The DUAL JOBS array contains job numbers for any weeks when the respondent worked at more than one job. There can be 7936 variables in the DUAL JOBS array - up to four for each of the 1984 weeks from 1/1/78 to 12/24/2015.[2] [5]DUAL JOBS array variables are present if a dual job was reported.[3]

The codes are as follows:

  0 = no dual job
  >100 = dual job year and job number

For example, if a respondent worked at three jobs at the same time, the code for the lowest job number would be in the WEEKLY LABOR STATUS array, and the codes for the other two jobs would be in the DUAL JOBS array (see item 3 in the user notes below). If the three jobs that the respondent held during week 190 from the 1981 (round 3) survey were jobs 1, 5, and 6, then WEEKLY LABOR STATUS would contain the value '301' for that week, and two DUAL JOBS array variables for week 190 would contain the values '305' and '306'.

User Notes

A few additional notes are in order:

1. The maximum number of dual jobs accounted for is 4. The variable descriptions for variables in the WORK HISTORY - DUAL JOBS area of interest indicate the relevant job number and week.

2. The DUAL JOBS array does not provide labor force status in the detailed manner of the WEEKLY LABOR STATUS array. It contains only second, third, fourth, and fifth job numbers for weeks in which the respondent reports more than one employer.

3. Users should be aware that it is possible in survey years 1979-92 for the CPS job number to appear in the DUAL JOBS array instead of the WEEKLY LABOR STATUS array, as would be expected. In most cases, the CPS job will be the lowest number job for a given year. However, this is not always the case. Each year contains a relatively small number of cases for which JOB #1 is not the CPS job. For these cases, the job number assigned by the work history program will not necessarily be the lowest one for that year. In cases for which the CPS job is not held simultaneously to any other job, the job number for the CPS job will appear in the WEEKLY LABOR STATUS array as expected. However, in cases for which the CPS job is held simultaneously with another job with a lower job number, the possibility exists that the job number for the CPS job will appear in the DUAL JOBS array instead of the WEEKLY LABOR STATUS array. Mechanical changes implemented in the 1993 CAPI instrument to ensure that the CPS job is always the first job have virtually eliminated this possibility from 1993 forward.

Work History non-weekly array created

Non-weekly array variables produced by the work history programs are listed below by Work History area of interest. Variables marked with an asterisk (*) contain an actual consecutive week number, ranging from week number 0-1984, with the week of January 1, 1978, being week #1. Week #0 represents information for time prior to that date.

Area of interest: WORK HISTORY-MAIN-CREATED

TENURE[#]

Total weeks tenure at each job as of interview date

MILWK-SLI

Weeks of active military service since date of last interview

WKSWK-SLI

Number of weeks worked since date of last interview

HRSWK-SLI

Number of hours worked since date of last interview

WKSUEMP-SLI

Number of weeks unemployed since date of last interview

WKSOLF-SLI

Number of weeks out of the labor force since date of last interview

WKSUNACCT-SLI

Percentage of weeks unaccounted for in calculating weeks worked since date of last interview

MILWK-PCY

Weeks of active military service in past calendar year

WKSWK-PCY

Number of weeks worked in past calendar year

HRSWK-PCY

Number of hours worked in past calendar year

WKSUEMP-PCY

Number of weeks unemployed in past calendar year

WKSOLF-PCY

Number of weeks out of the labor force in past calendar year

WKSUNACCT-PCY

Percentage of weeks unaccounted for in calculating weeks worked in past calendar year

WKSSINCELI

Number of weeks since date of last interview

JOBSNUM

Number of jobs ever reported as of interview date

Area of interest: WORK HISTORY-MAIN-JOB INFORMATION-[YEAR]

HRP]#]

Usual wage earned at each job converted to an hourly rate

Area of interest: WORK HISTORY-HISTORY

  LASTINT_WK#_[YEAR]* Week of last interview
  CURRINT_WK#_[YEAR]* Week of current interview

Area of interest: WORK HISTORY-CALENDAR YEAR

  CAL_YEAR_JOB[#]_[YEAR] Job number that is loaded into the WEEKLY LABOR STATUS array for each job. The 1st two digits of the number are the year (01 thru 25) and the 2nd two digits are the job for that year (job 01 thru 10)
  CAL_YEAR_JOBS_[YEAR] Number of jobs in past calendar year
  WKS_NWMISSC_[YEAR] Percentage of weeks not employed in past calendar year that cannot be split between unemployed and out of the labor force

Area of interest: WORK HISTORY-JOBS

  START_WK#_[YEAR]_JOB#[##] Starting week of each job
  STOP_WK#_[YEAR]_JOB#[##] Stopping week of each job
  PER[#]_START_[YEAR]_JOB#[##] Starting week of each period not working for each job
  PER[#]_STOP_[YEAR]_JOB#[##] Stopping week of each period not working for each job

Area of interest: WORK HISTORY-GAPS BETWEEN JOBS

  BSTART_[YEAR]_PERIOD[#] Week started each period not working between jobs
  BSTOP_[YEAR]_PERIOD[#] Week stopped each period not working between jobs.

Area of interest: WORK HISTORY-SINCE LAST INTERVIEW

  LASTINT_#JOBS_[YEAR] Number of jobs since the date of the last interview
  WKS_NWMISSL_[YEAR] Percentage of weeks not employed since the date of the last interview that cannot be split between unemployed and out of the labor force

Area of interest: WORK HISTORY-MILITARY

  MIL_START1_[YEAR] Starting week of first period of active military service.
  MIL_START2_[YEAR] Starting week of second period of active military service.
  MIL_STOP1_[YEAR] Stopping week of first period of active military service.
  MIL_STOP2_[YEAR] Stopping week of second period of active military service.

 

NLSY79 Main Data Work History variables

A third set of variables are either used in the Work History programs, or are basic, commonly used job-specific and gap-related survey items that were at one time duplicated on the separate Work History data sets prior to the 1979-2000 release. When the Work History data became part of the general public 1979-2000 release, these variables were assigned to areas of interest titled WORK HISTORY -- MAIN -- JOB INFORMATION [YEAR], to make it easier for historical data users to recreate the separate Work History data files they may have been working with up to that point. These areas of interest continue to be maintained. Click here to access a table containing these variables, with example reference numbers from the most recent round.

WORK HISTORY PL/1 PROGRAMS

The PL/1 programming used to create the work history variables through 1994 is available to researchers. These programs can be examined by those who desire details about the creation of the work history variables not included elsewhere in this appendix. Due to the length of these programs, they are not printed in this document. A file with these programs in chronological order by survey round (Addendum to Appendix 18) is available in electronic form. 

VARIABLES USED IN CREATION OF 1996 AND SUBSEQUENT WORK HISTORY DATA FILES

Beginning in 1996, the work history programming was converted to SQL programming. The SQL programs, which mirror the older PL/1 program, is not available to users. However, the Work History Input Variables 1996-Present Table lists the variables used as inputs to the SQL programs. Users who need more information should contact NLS User Services.

Users should be aware that not all of variables listed in the table appear in the NLSY79 public release data file. Variables with no valid data for any respondent, jobs 6-10, within-job gap 4 and between-job gaps 5-6 are not currently included in the main file.

Endnotes

[1] All week number references in this program are relative to 1/1/78 and end with the most recent interview date. A week #0 is included at the beginning of the week-by-week array structures to indicate time prior to 1/1/78. Users are discouraged from incorporating data contained in this week in analysis. Researchers should instead use information from the 1979 interview concerning labor force activity prior to 1/1/78 in order to construct event histories of a more thorough nature. (Some information concerning labor force activity for respondents prior to the time frame of the initial 1979 interview is asked on an age restricted basis for respondents still in their teens at the time of interview.)

[2] See footnote 1.

[3] All variables have standard missing value codes unless otherwise noted.

[4] While variables were added for week through the end of 2015, the final 2014 (round 26) interviews were conducted in October 2015. Therefore, valid data are only present through variables for week #1973 in the current data set. Valid data for weeks #1974-1984 will be filled in with information from future interviews. The maximum week number variable in a Dual Jobs array is week #1971, as no one reported multiple jobs in weeks #1972-1984.

[5] See footnote 4.