NLSY79 Appendix 9: Linking Employers from OnJobs Section to Employer Supplement and Through Survey Years

NLSY79 Appendix 9: Linking Employers from OnJobs Section to Employer Supplement and Through Survey Years

This appendix contains several components:

For more information on these and other employer-related topics, consult the Jobs & Employers pages and Employment section of the NLSY79 Topical Guide.

Questionnaire Modules

OnJobs Module

In the OnJobs module, a list of employers for whom the respondent worked between the previous and current interviews is built (sorted most recent to least recent).   

  • First, the list of employers with whom the respondent was active at the date of last interview ("DLI" employers) are verified and corrected if necessary. 
  • Second, respondents are asked if they worked again for any employers they were associated with prior to the last interview ("PDLI" employers). 
  • Third, respondents report any new employers ("NEW" employers) that are not on either the "DLI" or "PDLI" employer list. 

The result is a complete list of employers for whom the respondent worked between the previous to current interview. If multiple employers were reported, the list is then sorted from most to least recent stopdate, creating the final list or "roster" of ES employers for the current interview.

Before the 1979-2018 data release, and particularly for respondents with multiple employers, researchers have not been able to definitively link information collected in the OnJobs module to specific employers in the ESs. Prior to 2002, data produced from the OnJobs modules was limited both in quantity and analytic utility. However, beginning in 2002, questions were added to the OnJobs modules to establish and verify a "job type" (traditional, non-traditional or self-employment) for each employer. Researchers have been interested in linking this more substantive information to specific ES employers. The 1979-2018 data release contains variables (described below) that make this possible.

Employer Supplements

An ES is administered for each employer on the final roster that results from the OnJobs module. Respondents are asked to provide extensive employer-related information related to each employer. This information varies through survey years. The final job type determined for each job is available in the ES for survey years 2002-2018. However, the questions used to establish the job type are not available in the ES. The current data release includes variables that allow researchers to link data in the OnJobs module and to the corresponding ESs. A description of these variables follows.

Variables Linking OnJobs and Employer Supplement Employer Data

For the first time with the 2018 data release, the NLSY79 data includes several variables linking employer data collected in the OnJobs module with the corresponding ES. 

  • DLILINK.## - contains DLI employer loop number in OnJobs module corresponding to  ES ## (2002-2012). Qnames Q6-8[].## contain job type and verification data for DLI employers.
  • PDLILINK.## - contains PDLI employer loop number in OnJobs module corresponding to ES ## (2002-2012) Qnames Q6-16[].## contain job type and verification data for PDLI employers.
  • NEWLINK.## - contains NEW employer loop number in OnJobs module corresponding to ES ## (2002-2012). Qnames Q6-27[].## contain job type and verification data for NEW employers.
  • EMPLINK.## - contains loop number in OnJobs module corresponding to ES ## (2014-2018) (DLI, PDLI and NEW employer loops in OnJobs module were collapsed into one loop beginning in 2014)

Consider a respondent with the following characteristics and reflected in Table 1 below. At the 2008 interview, this respondent confirms two DLI employers and reports the stopdates in Table 1. S/he also reports returning to a PDLI employer for a period between the 2006 and 2008 interview, stopping work again on the date in Table 1. In addition, a NEW employer is reported with the stopdate in Table 1. Once these employers are confirmed, the job type questions would be asked in their entirety for newly added employers, or confirmed and updated if necessary, for employers for which a job type was previously established.

TABLE 1: Example: 2008 Respondent OnJobs to Employer Supplement Links

OnJobs Employers Reported

Stopdates reported (final roster is sorted by stopdate)

ES Number (after sorting final roster by stopdate)

DLILINK.## (## = ES number)


(## = ES number)

NEWLINK.## (## = ES number)

DLI emp #1






DLI emp #2






PDLI emp #1






NEW emp #1






In the example in Table 1:

  • Data in OnJobs DLI employer #2 (DLI loop #2) corresponds to ES #1
  • Data in OnJobs PDLI employer #1 (PDLI loop #1) corresponds to ES #2
  • Data in OnJobs NEW employer #1 (NEW loop #1) corresponds to ES #3
  • Data in OnJobs DLI employer #1 (DLI loop #1) corresponds to ES #4

Process for Linking Jobs Through Survey Years

Beginning in July 2013, the comprehensive "Employer History" roster has been made available to data users. This roster not only establishes links between employers through multiple survey years, but compiles a large amount of information about employers from one survey year to another into a single record for each employer. For further information about the Employer History roster, see Appendix 28: Employer History Roster.

It is still possible for users to link the respondents' employers from each contiguous survey year to the next using the traditional method. This appendix describes the traditional job linking process.

Comparable variables exist for each employer in all survey years, allowing a link to be established through all contiguous interview years during which the respondent reported working for a specific employer.

Use the variables with question names beginning with "PREV_EMP." All of these previous employer variables have a reference number that begins with "W." For example, the variables listed below in Table 2 relate to employers reported during the 1990 interview.

Table 2. Variables identifying job number assigned in previous interview

Reference #


Variable Title
















These variables identify the number that a job was assigned in the previous interview year, if that job was reported. If these variables contain a valid missing code (-4), then the job was not reported in the previous interview year (1989) and therefore cannot be linked to any employer in the previous year. This is essentially a "new" employer, reported for the first time during the current survey year (or possibly an employer reported before the previous interview). If any of these variables contains a valid number (1 or greater), this is the number of that job in the previous interview year. For example, if W05057.00 contains a "2", this would mean that employer #1 in 1990 is the same employer as employer #2 from 1989. One could then attach information from employer #1 in 1990 to information from employer #2 in 1989 as a continuing record of the respondent's experience with that employer. Using corresponding variables through contiguous interview years, information for an employer can be traced back through the first time the employer was ever reported by the respondent.

Of course, forward linking of employers can be accomplished in much the same way, using the same set of Previous Employer variables. For instance, to link information about employer #2 in 1989 with its continuation in 1990, one would search the 1990 Previous Employer Number variables for the number "2." Thus, a "2" in variable W0505900 would indicate that employer #3 in 1990 is the continuation of employer #2 from 1989.

This procedure works through contiguous survey years, even if the respondent has skipped interviews and the survey years are not consecutive. For example, if a respondent was interviewed in all years from 1985-1990, a direct match can not be made between an employer reported in 1990 and one reported in 1985 without first establishing matches (or the lack thereof) through all intervening years. However if a respondent was interviewed in 1985, and not again until 1990, a link between employers reported in these two years would be accomplished in the same manner as that described above between 1989 and 1990, as there would be no intervening year(s) to interfere with a direct match.

User Notes

Users should be aware of several data characteristics:

First, the NLSY79 employment history data are employer based. All references to a "job" should be understood as a reference to an employer. Information about work duties and positions and/or changes in duties or position performed or held during the respondent's tenure with a specific employer is collected as part of the record for that specific employer. For example, a respondent may regard him/herself as having held a number of "jobs" or positions with employer #1. However, any information collected about these different positions would all be regarded as information about employer #1.

The data for many survey years contain multiple versions of the PREVIOUS JOB NUMBER variables for employer matching. However, the PREVIOUS JOB NUMBER variables are compiled as part of the Work History programming and (as signified by reference numbers beginning with "W" consolidate this information into a single item for each employer for each survey year. Examples of these for 1990 are listed above in Table 2.

In the course of creating the Employer History roster mentioned earlier, a new more comprehensive version of the unique id was created for each job ever reported. These variables are called "EMPLOYERS_ALL_UID." These new unique employer ids are present for all jobs reported by all respondents since 1979. While these ids will usually match the id described in the paragraph above, they will not always match. Users should consider using the EMPLOYERS_ALL_UID.## variables wherever necessary, as these will generally be more consistent and available for all jobs.

This unique identification number consists of the first survey year in which the employer was reported, appended with the employer number in that survey year multiplied by 100. So for instance, an employer first reported as employer #1 in 1993 would have a unique employer id of 19930100. An employer first reported as employer #3 in 1994 would have the unique employer id of 19940300, and so on. This id number stays with the employer in subsequent survey rounds, whether or not more information is added to the employer record.

Users should note that previous versions of "unique ids" for employers were only available for respondents still eligible for interview in 1996 and subsequent survey years.