NLSY79

There are six types of variables present in the NLSY79 data. Some are the raw answers provided by the respondent, while others are constructed. Types of variables include:

1. Direct (or raw) responses from a questionnaire or other survey instrument
2. Edited variables constructed from raw data according to consistent and detailed sets of procedures, such as occupational codes, KEY variables, and so forth
3. Constructed variables based on responses to more than one data item, either cross-sectionally or longitudinally, and edited for consistency where necessary, such as variables on the NLSY79 Supplemental Fertility File ("Fertility and Relationship History/Created" area of interest in NLS Investigator)
4. Constructed variables from other sources, such as the County & City Data Book information present on the NLSY79 Geocode data files
5. Variables provided by an outside organization based on sources not directly available to the user, such as the high school survey and transcript data, scores from the Armed Services Vocational Aptitude Battery, and so forth
6. Data collected from or about one universe of respondents reconstructed with a second universe as the unit of observation, such as variables on the NLSY79 Child File

The type of variable impacts:

• the title or variable description naming each variable,
• physical placement of each variable within the codebook, and
• location of a variable within a given area of interest.

Reference numbers

Every variable in the main NLSY79 data files has been assigned a reference number or identifier that determines its relative position within the data file and NLS documentation system. Persons contacting NLS User Services should be prepared to discuss their question or problem in relationship to the reference number(s) of the variable(s) in question.

Once assigned to variables within the NLSY79 data files, reference numbers remain constant through subsequent revisions of the files. Reference numbers are assigned sequentially, with variables referring to the first survey year having a lower reference number than those variables specific to the second year and so forth.

Occasionally variables are created in a year later than that in which the data were actually collected. These variables are frequently given a reference number with a decimal value that reflects the year in which the actual data were gathered rather than the year the created variable was constructed, for example, R01461.01. Beginning with the 1993 survey, decimals are also used to indicate that more than one variable has been derived from a single question.

Variable descriptions or variable titles

Each variable within NLSY79 main file data files has been assigned an 80 character summary title that serves as the verbal representation of that variable throughout the documentation.

Variable titles are assigned by CHRR archivists who endeavor, within the limitations described below, to capture the core "content" of the variable and to incorporate within the title:

1. "NLS Investigator areas of interest" that facilitate easy identification of related variables,
2. "Universe identifiers" that specify the subset of respondents for which each variable is relevant, and
3. "Reference periods" that indicate the specific period of time (e.g., survey year, calendar year) to which the data pertain for some variables. Universe identifiers and reference periods are discussed below.

Universe identifiers

If two ostensibly identical variables differ only in that they refer to different universes, the variable title will include a reference to the applicable universe by either appending in parentheses to each title the appropriate universe (Example 1) or by identifying the universe before the variable title (Example 2).

• Example 1: 'Did R Have Any Job since Last Int? (Unemployed or OLF) (1994)'
• Example 2: 'Female - Number of Children R Has Had since Last Interview'

Reference periods

Variable descriptions may include a phrase indicating the time period to which the data refer. When a date follows a verbal description of a variable and is preceded by the prepositional phrase "in 19XX," the date identifies the calendar year for which the relevant information was collected.

• Example: 'Received Income from Child Support in 1991?' This 1992 survey question refers to child support payments received in calendar year 1991.

Variables with similar content, such as information on respondents' labor force status, may have completely different titles, depending on the type of variable (raw versus created). In addition, such variables may be located within different NLSY79 areas of interest.

• Example 1: 'Employment Status Recode' (ESR), in 1979-98 and 2006, is the created or reconstructed version of the 'Activity Most of Survey Week' raw variable. The 'Activity' variable is derived from the first question of the full series of questions used by the Department of Labor (DOL) to obtain employment status; the title reflects questionnaire content. ESR, on the other hand, reflects the procedure used to recode the 'Activity' variable. This produces a constructed variable for all respondents based upon responses to the 'Activity' question and all other questions used by the DOL to obtain employment status. These other questions serve to qualify and refine employment status beyond the answer to the initial 'Activity' question.
• Example 2: NLSY79 raw fertility variables appear within the various "Children," "Birth Record," or "Birth Record xxxx" areas of interest while edited and constructed versions of these variables appear within the "Fertility and Relationship History/Created" area of interest.

Finally, different archivists, for a period of more than 20 years, have performed the task of assigning variable descriptions to data. While every effort has been made to maintain consistency, users may find some differences in variable title and area of interest assignment.

New variables created by researchers

Researchers sometimes use the NLS public datasets to generate a new variable to use in their research. In some cases, researchers like to make that new variable publicly available (through their own data repository) so that it can be easily accessed for follow-up studies. This is permissible as long as researchers are using public NLS data (rather than restricted) and that they make it clear they are the author of the variable rather than the NLS team.

The primary variables found within the main data set are derived directly from survey instruments, such as questionnaires, household interview forms, and so forth. This section describes each of the NLSY79 instruments in the order that they appear in the following list.

Types of NLSY79 survey instruments and user aids

• 1978 Household Screener; Household Interview Forms
• Interviewing Aids
  • Face Sheet
  • Information Sheet
  • Children's Record Forms (CRF)
• Questionnaires
• Questionnaire Supplements
  • 1980 Illegal Activities Form J
  • Employer Supplements (ES)
  • 1983 Fertility Supplement
  • Confidential Abortion Forms
  • 1988, 1992, 1994, and 1998 Drug Use Supplement
  • 1988 Childhood Residence Calendar
• Supplemental data collections
  • High School Survey
  • 1980-1983 Transcript Surveys
  • ASVAB
• Interviewer Reference Manuals (Q by Qs) and CAPI Help Information

This section also explains the conventions used in the NLSY79 documentation system to identify questionnaire items from some of the primary survey instruments. An additional document, the interviewer reference manual, provides background information on specific survey instruments.

A unique set of survey instruments has been used during each survey year to collect information from respondents. The term "survey instrument" is used to refer to:

1. the questionnaires that serve as the primary source of information on a given respondent
2. questionnaire supplements fielded during select survey years that contain additional sets of questions
3. documents such as the household interview forms or household record cards that collect information on members of each respondent's household

Users should be aware that, while the source of the majority of variables in the main NLSY79 data files is the questionnaire or one of the other survey instruments, certain NLSY79 variables are created either from other NLSY79 variables or from information found in an external data source (see Types of Variables).

Household information

Each NLSY79 interview includes the collection of information on the members of each respondent's household. For NLSY79 respondents, such household data are collected prior to the administration of the main questionnaire and for many years used separate survey instruments called the Household Interview Forms. Both the instruments used for the yearly household data collection and the household screening instruments that were used to draw the samples of respondents are described below.

NLSY79 1978 Household Screener and Interviewer's Reference Manual

This document (fully titled NLSY-National Longitudinal Survey of Labor Force Behavior Interviewer's Manual-Household Screening, NORC 1978) contains detailed information on the 1978 screening of households conducted by NORC from which the civilian youth samples (the cross-sectional and supplemental samples) were drawn. It provides a copy of the short 25-question screener, question-by-question specifications for administering the form, and a sample completed screener. Most of the information collected on each respondent during the screening is presented within the data set. The screener is the source for important data such as the sex and race or ethnicity variables that were used to assign each respondent to a specific NLSY79 subsample, as well as the relationship codes (for example, brother, sister, husband, wife) that allow researchers to identify related NLSY79 respondents who shared a household at the time of the screening.

Question numbering

Question numbers for the 1978 screener were arbitrarily assigned by NORC using an artificial questionnaire section number that followed the last section of the 1979 questionnaire ("Section 25" for all screener variables) even though the actual administration of the screener preceded that of the 1979 questionnaire.

Users should note that screener questions are identified within the documentation as 1979 variables even though these data were collected during 1978. Most variables from the screener use the phrase HOUSEHOLD SCREENER at the beginning of the variable title, appear physically within the codebook after the 1979 household record series, and have been placed within the "1978 Screener" and "Household Record" areas of interest.

Household interview forms

Yearly household information for the NLSY79 is collected from either the respondent or the head of household prior to the administration of the main questionnaire. NLSY79 Household Interview Forms are used to:

1. enumerate all persons currently living in the respondent's household
2. record information about each person's age, highest grade completed, work experience in the past year, and relationship to the respondent
3. collect, during the 1979-1986 surveys, certain family income information

Information on household members is collected using the questions on the Household Interview Forms; however, much of the information is actually recorded on the "Household Enumeration" section of the Face Sheet discussed below.

During the 1979-1986 interviews, different versions of the Household Interview Forms were administered depending upon the type of residence of the respondent. Version A was used if the respondent was living with his or her parents (or in-laws), in which case the interview was conducted with the respondent's parents (or in-laws) in order to gather information on household income sources. Version B was used if the respondent was living in group quarters, such as a dormitory or the military, or in temporary facilities, such as a hospital or prison, and was administered to the respondent. If the respondent had a permanent residence elsewhere, the household interview gathered information about that household. Version C was administered to the respondent if he or she was living in his or her own dwelling unit, military family housing, an orphanage, a religious institution, or other individual quarters or was the head of a family unit. Table 1 in the Household Composition section of depicts, by survey year, the universe and residential unit(s) specific to each form.

During the first eight survey rounds, many respondents were younger than 18 and living with their parents; thus, Version A was frequently used. Beginning with the 1987 survey, all respondents were 21 or older and living predominantly on their own; consequently, the household interview forms were consolidated into a single version. For 1979-1986, these forms appear as separate documents. Beginning with the 1987 interview, household interview questions were incorporated within each year's questionnaire. Some variation in administration of these forms has occurred over survey years. Users should refer to each survey year's Interviewer's Reference Manual for more information.

Interviewing aids

Certain instruments used during fielding of the NLSY79 provide researchers with interview- and respondent-specific information that appears as variables within the NLSY79 data files.

Face Sheet

Immediately prior to fielding, a Face Sheet is computer-generated for each respondent and forwarded to the interviewer assigned to that case. The Face Sheet contains:

1. various items of respondent-specific information (name, address, phone number)
2. information about each member of the household or family unit as of the last interview (full name, sex, relationship to youth, education, and whether the household member worked during the year), generated from the most recent administration of the Household Interview Forms
3. a historical overview of previous interview rounds (whether the respondent refused to be interviewed, the respondent was interviewed after initially refusing, the interview was complete or incomplete, and so forth)
4. for the 1980-1986 survey years, information on the version of the Household Interview Form that was used in the previous interview

This information is used to alert the interviewer and field manager to potential problems, assist them in preparing a successful location and fielding strategy, and provide details necessary to conduct an efficient interview, such as a listing of previous employers. Information about the respondent's household and family unit from each survey year's Face Sheet can be found by searching the "Household Record" area of interest with NLS Investigator. Sample Face Sheets for most survey years can be found in the various Interviewer Reference Manuals.

Information Sheet

This document contains data on the respondent from the previous interview that will be referred to and used to update information during the interviewing process. Items found on this document include marital status, high school completion status, university last attended, names of previous employers, training program enrollment, and pregnancy status. This information enables the interviewer to accurately route the respondent through the relevant sections of the questionnaire and provides on-the-spot reconciliation of earlier errors. Information Sheet items appear within the NLSY79 data set ("Last Interview Information" area of interest in NLS Investigator). Beginning with the 1993 interviews, the information sheet is incorporated into the CAPI instrument. Sample Information Sheets can be found in the Interviewer Reference Manuals. In CAPI surveys, information sheet data are stored electronically on the interviewer's laptop and accessed by the survey program during the interview; no paper information sheet is used.

Children's Record Forms (CRF) (1985-1992)

This interviewing aid containing information on biological (collected each survey) and nonbiological (that is, adopted or step-; collected biennially) children was used in the 1985-1992 surveys to:

1. provide identification numbers, names, dates of birth, sex, and deceased/adopted status for each child
2. identify special sections of the main questionnaire (such as immunization, feeding, and so forth) that needed to be administered for particular children

Sample Children's Record Forms can be found in the Interviewer's Reference Manuals. Beginning with the 1993 interviews, this form is incorporated into the CAPI instrument. As with information sheets, these data are automatically accessed by the survey program during CAPI interviews, so the hard copy CRF is no longer needed.

Questionnaires

There are separate and distinctly different questionnaires for each survey year of the NLSY79. Each questionnaire is organized around a set of topical subjects, the titles of which usually appear on either the first page of each section of the questionnaire or as a header.

NLSY79 questionnaires record:

1. interview dates
2. responses to the topical survey questions (see discussion below)
3. locating information which will assist NORC in finding the respondent for the next interview
4. interviewer remarks on such topics as the race and sex of respondent, language in which the interview was conducted, interviewer's impressions, and so forth

Show cards

These are interviewing aids used in conjunction with the questionnaire and list the possible response categories for selected questions. Show cards help the respondent keep the more complicated response categories in mind.

NLSY79 questionnaires explore the following core topics:

• current labor force status
• jobs and employers
• work experience and attitudes
• training
• assets and income
• family background
• marital history
• fertility
• regular schooling
• military service
• health

Additional sets of questions have been fielded during select survey years on such topics as:

• childcare
• alcohol use
• drug use
• job search methods
• educational/occupational aspirations
• school discipline
• pre-and post-natal health behaviors
• delinquency
• childhood residences

During the 1979-1992 paper-and-pencil (PAPI) interviews, questionnaires and other survey instruments were preprinted paper products used during fielding. With the advent of computer-assisted interviewing (CAPI) in 1993, the "questionnaire" became a series of visual screens that not only told the interviewers what questions to ask but provided helpful instructions on how to administer the interview. Separate supplemental documents such as the job-specific Employer Supplements were integrated into the electronic main questionnaire. NLSY79 CAPI questionnaires incorporate some helpful elements of the traditional codebook, with reference numbers assigned to variables and greater specificity on coding and universes provided within each codeblock.

Question numbering

The conventions used to assign question numbers within the NLSY79 documentation system vary by survey year and are based on various combinations of the questionnaire section number, the question number, or the deck and column numbers (Table 1). Users can locate a variable within the codebook--which represents each question fielded in the same order as it appears within the questionnaire--by finding the question number which appears (in parentheses) to the right of each reference number.

Deck and column numbers are vestigial items that were used to locate the data when it was input on punch cards. The deck numbers are printed at the upper right hand corner of each page in the survey instruments and at the beginning point for each new deck for the 1980 through 1992 instruments. The column numbers are printed to the left of the response categories. If the variable contains more than one digit, the column reference is to the starting column for that variable. 

Questionnaire supplements

Separate instruments called "supplements" have been used since the onset of the NLSY79 to administer distinct sets of questions. The NLSY79 has made extensive use of supplements for collecting information from separate universes such as schools or children or for administering confidential sets of questions on illegal activities or abortion. The following section describes each supplemental instrument used for the NLSY79. The use of such separate supplements has diminished with CAPI-administered interviews. In the main youth and young adult instruments, all supplements are now incorporated as electronic modules in a questionnaire. Children still use multiple supplements, one self-report, one interviewer-administered, and one completed by the mother.

Illegal Activities Form J (1980)

This confidential questionnaire supplement, administered during the 1980 survey, contains a series of questions designed to collect information on the extent of respondents' participation in various delinquent and criminal activities such as:

• skipping school
• alcohol/marijuana use
• vandalism
• shoplifting
• drug dealing
• and robbery

This series supplements those on reported contacts with the criminal justice system collected within the main questionnaire.

Employer Supplement

Information about each employer for whom a NLSY79 respondent has worked since the last interview has been collected since 1980. One Employer Supplement is administered for each employer and contains questions about gaps when the respondent was not working, the number of hours worked, the type of work done, and the wages earned at that job. Note: Comparable information for the 1979 survey can be found in the "On Jobs" section of the main questionnaire and within the separate single sheet 1979 Employer Flap. Beginning with the 1993 CAPI interviews, all employer supplement questions appear within the body of the main questionnaire.

Question numbering

Five numbering systems have been used to identify questionnaire items within the Employer Supplement (Table 2). Although data from up to 10 jobs are collected, the main data set includes information on only the first five jobs since few individuals work at more than five jobs between interviews. Data on all ten jobs are used to construct a series of summary variables for hours and weeks worked; see the Labor Force Status, Time & Tenure with Employers, and Work Experience sections for more information.

Fertility Supplement (1983)

Respondents (both male and female) who were not interviewed during 1982 were administered a special set of supplementary fertility questions during the 1983 survey. The Fertility Supplement was designed to collect complete fertility data, including all live births for males and females, and all pregnancy losses and contraception between pregnancies for females. For those not interviewed in 1982, these questions replaced the fertility questions found in Section 10 of the 1983 questionnaire.

Confidential Abortion Forms

Biennially beginning in 1984, female NLSY79 respondents have completed a short confidential abortion form which elicited information on the number and dates of each abortion. Copies of these supplementary questions are provided within the survey instrument sets. The 1984 form also collected information on the dates that respondents left school prior to 1979 if leaving school was associated with early childbearing. Beginning in 2002, the abortion form was included in the main instrument. 

Drug Use Supplement (1988, 1992, 1994, and 1998)

The 1988 supplement contains the confidential set of drug use questions which were, through a random assignment process, self-administered by the respondent in half of the cases and administered by the interviewer in the other half. Questions were asked on age at first use of marijuana and cocaine, extent of lifetime and most recent use, and method(s) practiced in using cocaine. The 1992 and 1994 supplements contain the confidential set of questions on respondents' use of cigarettes, alcohol, marijuana, cocaine, or other drugs. Users should note that while the 1988 and 1992 supplements are bound as separate booklets, the 1994 and 1998 supplements are bound with the main questionnaire.

Childhood Residence Calendar (1988)

The 1988 questionnaire contained a special section detailing the living arrangements of respondents from birth through age 18. The Childhood Residence Calendar, the interviewing aid used to collect these data, depicts for each year of life the type of parent (biological-, adoptive-, or step-) with whom each respondent lived for at least four months and, for those ages when he or she was not living with a parent, in what other arrangements the respondent resided, such as, with grandparents, foster parents, friends, or in a children's home, detention center, or other institution.

Supplemental data collections

High School Survey (1980)

A supplemental survey of the last secondary school attended by civilian NLSY79 respondents was conducted in 1980. This survey gathered information on each school's grading system, course offerings, dropout rate, student body composition, and faculty characteristics, as well as respondent scores from a variety of intelligence and aptitude tests. Copies of the high school survey instruments, the "School Questionnaire" and the "Student's School Record Information" form, are included within the documentation item called the NLSY High School Transcript Survey: Overview and Documentation. 

Transcript Surveys (1980-1983)

Transcript information on up to 64 courses was collected from high school records for civilian NLSY79 respondents who were expected to complete high school within the United States. A copy of the instrument used to collect transcript information, called the "Transcript Coding Sheet," is included within the NLSY High School Transcript Survey: Overview and Documentation (see School & Transcript Surveys Documentation in the NLSY79 Codebook Supplement).

ASVAB

The Armed Services Vocational Aptitude Battery (ASVAB) was administered to most NLSY79 respondents in 1980 as part of a Department of Defense effort to renorm this military enlistment test. The scores from this supplemental data collection are included in the NLSY79 data file. For details, see the Aptitude, Achievement & Intelligence Scores section.

Interviewer's Reference Manual (Question-by-Question [Q by Q] specifications)

Each questionnaire or set of survey instruments is accompanied by an Interviewer's Reference Manual. This document provides NORC interviewers with background information on the NLSY79 and detailed question-by-question instructions for administering and coding the questionnaire, Employer Supplement, Household Interview Forms, and other survey supplements. Separate Q by Q's exist for each survey year. Printed copies of the CAPI help screen information, which each interviewer could access during the course of the interview, replace the traditional interviewer's manual instrument beginning with the 1993 release.

• Household Interview Section for NLSY79 Rnd 30 Questionnaire

• Migration History and Family Background Section for NLSY79 Rnd 30 Questionnaire

• Marital History Section for NLSY79 Rnd 30 Questionnaire

• Military Section for NLSY79 Rnd 30 Questionnaire

• On Jobs Section for NLSY79 Rnd 30 Questionnaire

• Employer Supplement Section for NLSY79 Rnd 30 Questionnaire

• Business Ownership Section for NLSY79 Rnd 30 Questionnaire

• Business Match Section for NLSY79 Rnd 30 Questionnaire

• Gaps Section for NLSY79 Rnd 30 Questionnaire

• Perceived Discrimination Section for NLSY79 Rnd 30 Questionnaire

• Training Section for NLSY79 Rnd 30 Questionnaire

• Spouse Labor Information Section for NLSY79 Rnd 30 Questionnaire

• Fertility Section for NLSY79 Rnd 30 Questionnaire

• Health Section for NLSY79 Rnd 30 Questionnaire

• Income and Recipiency Section for NLSY79 Rnd 30 Questionnaire

• Retirement Expectations Section for NLSY79 Rnd 30 Questionnaire

• Wills Section for NLSY79 Rnd 30 Questionnaire

• Interview End Section for NLSY79 Rnd 30 Questionnaire

• Locator Section for NLSY79 Rnd 30 Questionnaire

• Interviewer Remarks Section for NLSY79 Rnd 30 Questionnaire

The NLS program has established set procedures for ensuring respondent confidentiality and obtaining informed consent. These procedures comply with Federal law and the policies and guidelines of the U.S. Office of Management and Budget (OMB) and the U.S. Bureau of Labor Statistics:

• OMB procedures and federal laws
• Survey procedures
• Data handling

OMB procedures and federal laws

OMB procedures

The Office of Management and Budget (OMB) is responsible for setting overall statistical policy among Federal agencies. For example, OMB has established standards on collecting information about race and ethnicity, industry, occupation, and geographic location. OMB also has established standards on the manner and timing of data releases for such principal economic indicators as the gross domestic product, the national unemployment rate, and the Consumer Price Index. In addition, OMB sets standards on whether and how much respondents to Federal surveys can be paid for their participation, an issue of particular concern in the NLS program.

Another of OMB's responsibilities is to review the procedures and questionnaires that Federal agencies use in collecting information from 10 or more respondents. Federal data collections reviewed by OMB include administrative data, such as the tax forms that the Internal Revenue Service requires individuals and corporations to complete. OMB also reviews all censuses and surveys that Federal agencies conduct, either directly or through contracts.

Surveys that are funded through Federal grants to universities and other organizations generally do not have to undergo this OMB review process unless the grantee in turn contracts with a Federal statistical agency such as the Census Bureau to collect the data. In place of OMB review, surveys funded through grants typically must undergo a competitive peer-review process established by the agency administering the grant, and that review process examines the procedures for maintaining respondent confidentiality and obtaining the informed consent of the participants. In addition, such surveys also typically are scrutinized by an institutional review board established at the grantee's institution.

OMB examines a variety of issues during these reviews, such as the:

• amount of time (and money, if any) that the agency collecting the information estimates respondents will spend to provide the requested information
• agency's efforts to reduce the burden on respondents of providing the information
• purpose and necessity of the data collection, including whether it duplicates the objectives of other Federal data collections
• ways in which the agency obtains informed consent from potential respondents to participate in the data collection
• policies and procedures that the agency has established to ensure respondent confidentiality
• statistical methods used to select representative samples, maximize response rates, and account for nonresponse
• payment of money or the giving of gifts to respondents
• questionnaire itself, including the quality of its design and whether it includes questions that respondents may regard as sensitive

These OMB reviews are very thorough. From the time an agency prepares an OMB information collection request until the time OMB approves the data collection, the process typically takes 7 months or more and includes multiple layers of review within the agency and at OMB. These reviews are helpful in improving survey quality and ensuring that agencies treat respondents properly, both in terms of providing them with information about the data collection and its uses and protecting respondent confidentiality.

The review process also provides the general public with two opportunities to submit written comments about the proposed data collection. The agency conducting the data collection publishes a notice in the Federal Register describing the data collection and inviting the public to request copies of the information collection request, questionnaires, and other materials that the agency eventually will submit to OMB. The public is invited to submit written comments to the agency sponsoring the data collection within 60 days from the time the Federal Register notice is published. In the history of the NLS program, the public very rarely has submitted comments to BLS, but when comments are received, they are summarized in the information collection request that ultimately is submitted to OMB.

After the request has been submitted to OMB, the agency sponsoring the data collection then publishes a second notice in the Federal Register and invites the public to submit comments directly to OMB within 30 days. Again, in the history of the NLS program, the public very rarely, if ever, has submitted comments to OMB. Once OMB has received the information collection request, they have 60 days to review the package, ask follow-up questions, suggest changes (or, occasionally, insist upon changes) to the survey questionnaire or procedures, and ultimately grant approval.

Respondents' advance letter

After OMB grants approval, the sponsoring agency can begin contacting potential respondents and collecting information from them. The process of contacting potential NLS respondents begins with sending them an advance letter several weeks before interviews are scheduled to begin. The advance letter serves several purposes. The obvious purpose is to inform respondents that an interviewer will be contacting them soon, but BLS and the organizations that conduct the surveys for BLS also use the letter to thank respondents for their previous participation and to encourage them to participate in the upcoming round. Another important objective of the advance letter is to remind respondents that their participation is voluntary and to tell them how much time the interview is expected to take. The letter also explains to respondents how the data will be used and how respondents' confidentiality will be protected by BLS and the organizations that conduct the surveys for BLS. An example of an advance letter, along with the confidentiality statement that appears on the back of the letter, is shown in Figure 1.

Institutional review boards

In addition to OMB review, the NLSY79 is reviewed and approved by an institutional review board (IRB) at the institutions that manage and conduct the surveys under contract with BLS. Those institutions are The Ohio State University and NORC at the University of Chicago. BLS and OMB do not require these reviews; rather, the reviews are required under the policies of the universities. Obtaining approval from the IRBs involves completing a form signed by the Principal Investigator, providing a summary of the research project and submitting a description of the consent procedures and forms used in the survey.  Additional documentation includes a copy of any materials used to recruit respondents, a detailed summary of the survey questionnaire, and any other information regarding the risks to humans of participating in the survey. OMB must review all data collections for the NLSY79.

The NLSY79 project staff at The Ohio State University Center for Human Resource Research (CHRR) and at NORC obtain approval from their respective IRBs prior to the start of each round of data collection. Because each survey includes only an interview and no invasive medical procedures, the IRBs typically focus on respondent compensation, consent procedures, and confidentiality protections for special populations, such as incarcerated or disabled respondents. Prisons, schools, and other institutions in which NLSY79 sample members may reside often request the IRB approval statement and application as evidence that appropriate procedures are being followed and to judge whether to permit NLSY79 interviewers to have access to individuals for whom the institutions are responsible.

Federal laws

Two Federal laws govern policies and procedures for protecting respondent confidentiality and obtaining informed consent in the NLSY79 program: the Privacy Act of 1974 and the Confidential Information Protection and Statistical Efficiency Act (CIPSEA) of 2002.

The Privacy Act and CIPSEA

These two acts protect the confidentiality of participants in the NLSY79 and its associated Child and Young Adult surveys. CIPSEA protects the confidentiality of participants by ensuring that individuals who provide information to BLS under a pledge of confidentiality for statistical purposes will not have that information disclosed in identifiable form to anyone not authorized to have it.

In addition, CIPSEA ensures that the information respondents provide will be used only for statistical purposes. While it always has been the BLS policy to protect respondent data from disclosure through the Privacy Act and by claiming exemptions to the Freedom of Information Act, CIPSEA is important because it specifically protects data collected from respondents for statistical purposes under a pledge of confidentiality.

This law strengthens the ability of BLS to assure respondents that, when they supply information to BLS, their information will be protected. In addition, CIPSEA includes fines and penalties for any knowing and willful disclosure of specific information to unauthorized persons by any officer, employee, or agent of BLS. Since the enactment of the Trade Secrets Act and the Privacy Act, BLS officers, employees, and agents have been subject to criminal penalties for the mishandling of confidential data, and the fines and penalties under CIPSEA are consistent with those prior laws. CIPSEA now makes such fines and penalties uniform across all Federal agencies that collect data for exclusively statistical purposes under a pledge of confidentiality.

Survey interviewers are trained how to answer questions from respondents about how their privacy will be protected. Interviewers explain to potential respondents that all the employees who work on the surveys at BLS, NORC, and CHRR are required to sign a document stating that they will not disclose the identities of survey respondents to anyone who does not work on the NLS program and is therefore not legally authorized to have such information. In fact, no one at BLS has access to information about respondents' identities, and only a few staff members at NORC and CHRR who need such information to carry out their job duties have access to information about respondents' identities.

Interviewers also explain that the answers respondents provide will be made available to researchers at BLS and other government agencies, universities, and private research organizations, but only after all personal identifiers--such as names, addresses, Social Security numbers, and places of work--have been removed. In addition, the publicly available data files exclude any information about the States, counties, metropolitan statistical areas, and other, more detailed geographic locations in which respondents live, making it much more difficult to infer the identities of respondents.

Respondents are told that some researchers are granted special access to data files that include geographic information, but only after those researchers undergo a thorough application process at BLS and sign a written agreement making them official agents of BLS and requiring them to protect the confidentiality of respondents. In no case are researchers provided with information on the personal identities of respondents.

Finally, the reference in the questions and answers to the National Archives and Records Administration and the General Services Administration may be confusing to some potential respondents, because those Federal agencies are not involved in the administration of the surveys. Interviewers explain to respondents that NLS data and materials will be made available to those agencies because they are responsible for storing the Nation's historical documents. The information provided to those agencies does not include respondents' personal identities, however.

The organizations involved in the NLS program continuously monitor their security procedures and improve them when necessary. Protecting the privacy of NLS respondents entails considerable responsibilities for BLS, the organizations that conduct the surveys for BLS, and the researchers who use the data. Indeed, researchers in particular may become frustrated that they cannot obtain access to all the data that they want or that they must undergo a long review process at BLS to obtain some types of data. It is important to remember, however, that protecting respondent confidentiality must remain paramount. Any action that might jeopardize respondent confidentiality and erode the confidence of respondents could harm response rates in the NLS program and in other government or academic surveys. Thus, without the safeguards in place to protect respondent confidentiality, researchers would have far less data available to work with than they currently enjoy.

Contractors' role in maintaining respondent confidentiality

BLS, NORC, and CHRR are responsible for following the Federal requirements and maintaining their own security procedures. As mentioned earlier, all officers, employees, and agents of BLS are required to sign agreements stating that they will not disclose the identities of survey respondents to anyone who does not work on the NLS program and is therefore not legally authorized to have such information. Each contractor has in place procedures to ensure that the data are secure at each point in the survey process. (See the Data Handling section for more information.)

Survey procedures

Like all contractor staff, field interviewers are agents of BLS and are required to sign the BLS agent agreement before working on the NLSY79. All interviewers also must undergo a background check when they are hired. Confidentiality is stressed during training and enforced at all times. Field interviewers receive specific instructions in their reference manuals to remind them of the appropriate procedures when locating or interacting with respondents or contacts.

At the end of each interview, interviewers ask respondents to provide information on family members, friends, or neighbors who can be contacted if the interviewers are unable to locate the sample member in a subsequent round of interviews. The interviewers then use those contacts to help in locating sample members who have moved. When contacting a sample member's relatives, friends, or neighbors about the sample member's whereabouts, interviewers never disclose the name of the survey they are conducting. They are instructed to maintain the confidentiality of any relative, friend, or neighbor who provides information about the sample member's whereabouts.

Answering machines can pose problems when interviewers are contacting sample members because it is difficult to confirm that the interviewer is calling a sample member's correct telephone number or that other household members will not hear the message. For those reasons, interviewers are instructed not to leave messages on answering machines.

When interviewers contact the appropriate household, they ask to speak with the sample member. Interviewers introduce themselves and state the purpose of the call by saying that they are from the National Opinion Research Center at the University of Chicago and are calling concerning a national survey. The name of the survey is not disclosed to anyone but the sample member.

Special situations

The NLSY79 is a general population survey and includes a variety of sample members with special circumstances, such as incarcerated individuals, respondents in the military, other institutionalized persons, disabled persons, those with limited English proficiency, and so forth.

Incarcerated respondents

Incarcerated respondents constitute the largest group requiring special accommodations. The first challenge with incarcerated respondents is contacting them to schedule an interview. NLS interviewers must contact the prison administration to arrange for an interview, but the interviewers cannot legally reveal to the prison administration that the prisoner previously had participated in the survey without first obtaining the written, informed consent of the prisoner to reveal that information (Note: Data were incomplete for 2004 due to confidentiality concerns regarding inmates' participation in the NLSY79. A protocol was established for round 22 of the NLSY79).

The following steps are used for obtaining prisoners' consent:

1. Prisoners are first sent a letter reminding them about their previous participation in a NORC survey, but, in case the mail is monitored by prison staff, the letter does not name the survey or BLS so as not to reveal the prisoner's participation. The letter encourages the prisoner to participate in the upcoming round of the survey. It explains that NORC staff needs to set up an interview through the prison administration but that NORC cannot tell the prison administration about the prisoner's participation without the prisoner's informed consent. he letter then asks the prisoner to request a consent form by signing and dating an enclosed form letter and mailing it to NORC in a pre-addressed, postage-paid envelope. The letter reminds the prisoner that the mail at the institution may be monitored and explains that the consent form that NORC will send the prisoner will state the prisoner's name and the name of the survey. The letter emphasizes that, by returning the enclosed form letter, prison management or staff may learn that the prisoner is a participant in the survey.
2. If the prisoner chooses to send the form letter to NORC, NORC then sends the prisoner a cover letter and a consent form that names the specific survey. The prisoner is asked to sign the consent form and mail it to NORC in a pre-addressed, postage-paid envelope. Once NORC has received the signed consent form, NORC staff can contact the prison to request permission to interview the prisoner and learn about any restrictions that the prison administration may impose.
3. If the prison administration permits an interview and a date and time have been scheduled for the interview, NORC mails another letter to the prisoner. This letter serves two purposes. First, it tells the prisoner when the interview will take place. Second, it informs the prisoner in writing that the interview very likely will be monitored by prison that it is important to tell the prisoner in writing.

Once all of these steps are complete, the prisoner finally can be interviewed, but the NLS program takes additional steps to minimize the risk that prisoners might reveal illegal or illicit behavior in the presence of prison staff during the course of the interview.

As described later in this chapter, such sensitive questions are asked in the self-administered portions of the NLSY79. During these portions of the survey, the typical protocol for a respondent who is not incarcerated involves the interviewer turning the laptop computer around to enable the respondent to read the questions to him or herself and enter the answers directly into the laptop computer without the interviewer knowing the responses. (In fact, the interviewer does not even know which questions the respondent answered). In some relatively low-security correctional facilities, such as some county jails and halfway houses, this protocol still would be possible. In higher security facilities, the prison administrators would not permit the prisoner to touch the computer, so the questions either would have to be read to the respondent or skipped altogether.

NLS program staff have identified the questions that could be considered even moderately sensitive or risky for the prisoner to answer out loud. Given this examination of these questions, the NLS program has adopted the following protocol for administering sensitive questions to prisoners:

1. At the very beginning of the interview, the interviewer will indicate in the survey instrument whether a respondent is in a correctional facility of any kind and, if so, whether the facility permits the prisoner to touch the laptop and enter responses to the self-administered questions. For Federal prisons, the interviewer assumes that the prisoner is not permitted to touch the laptop.
2. If the facility permits the prisoner to enter responses to the self-administered questions directly into the laptop, then the full set of questions, including all of the sensitive questions, would be administered.
3. If the facility does not permit the prisoner to enter responses directly into the laptop, or if the interview is conducted over the telephone rather than in person, all survey questions will be asked orally by the interviewer, but the instrument is programmed to skip sensitive questions in which the prisoner might be asked about illegal or illicit behavior.

Military respondents

NLSY79 respondents who are in the military tend to be very cooperative and willing to participate in the surveys, but it sometimes can be difficult to locate and contact them, particularly if they are stationed outside the United States. It sometimes is necessary to seek the help of military or civilian staff in the Department of Defense to locate and contact military respondents, but NLS program staff first must obtain the military member's written, informed consent to reveal to Department of Defense staff that he or she previously had participated in the survey and is willing to be contacted to participate in future rounds of the survey.

Respondents with limited English proficiency

Some respondents lack fluency in English and are more comfortable using another language. It is not possible to accommodate all of the different languages other than English that respondents might speak, but the NLSY79 historically has made special arrangements for respondents and their parents who speak Spanish, the most commonly spoken language other than English among respondents. NORC staff members translate advance letters and other informational materials into Spanish to enable respondents and the parents of minor respondents to provide their informed consent based on information that is written in the language that they understand best. Survey questionnaires also have been translated into Spanish to ensure that the surveys are administered consistently, an alternative much preferable to having Spanish-speaking interviewers translate the English-language questionnaire during the interview. The first 20 rounds of the NLSY79 included a Spanish version of the questionnaire, but, because the number of respondents who speak only Spanish has continued to decline, it no longer is cost-effective to continue programming a computerized Spanish questionnaire. For that reason, Spanish questionnaires are not used starting with round 21 (2004) of the NLSY79. Advance letters and other informational materials still are available in Spanish, however.

Sensitive topics

The NLSY79 has included questions on income and assets, religion, relationships with parents and other family members, sexual experiences, abortion, drug and alcohol use, criminal activities, homelessness, runaway episodes, and other topics that are potentially sensitive for respondents to discuss. Respondents are advised at the start of the interview that they can choose not to answer any questions that they prefer not to answer. During training, interviewers undergo exercises to teach them how to allay the concerns of respondents about answering sensitive questions and encourage them to respond.  Interviewers are instructed not to coerce respondents into answering questions that they prefer not to answer, however.

All questions in the NLSY79 are read to the respondent by an interviewer. The respondent then provides an answer, and the interviewer records that answer on a laptop computer. For especially sensitive questions, some respondents might be reluctant to answer truthfully--or at all--if they have to tell an interviewer their answers, even though interviewers can face criminal and civil penalties if they disclose the respondents' identities or answers to anyone not authorized to receive that information.

Guidelines for emailing sample members

At the end of each interview, respondents are asked to provide information that will help interviewers contact them during subsequent rounds of the surveys. In addition to the information collected about relatives, friends, or neighbors, interviewers also obtain the email addresses of sample members who have them. During round 20 of the NLSY79 (conducted during 2002), the NLS contractors began using email as a means to contact a small number of sample members who were hard to reach by other means. The following guidelines were enacted to ensure confidentiality:

1. The name of the survey is not contained in the subject line or text of the email message. Some respondents may share the use of an email address with other household members, so the survey name is omitted from the message to prevent other household members from learning the specific name of the survey.
2. Email is sent from one main address. Field interviewers are not permitted to use their individual email accounts to contact respondents.

Respondents knowing respondents

One feature of the sample design in the NLSY79 is that there often are multiple respondents within the same original household, either siblings or, occasionally, spouses. It obviously is not possible in these cases to prevent family members from knowing that a relative is in the survey sample, but interviewers take steps to ensure that each respondent's answers remain private and are not revealed to other family members.

Consent from NLSY79 respondents

Respondents are able to review the confidentiality and consent information presented in the advance letter. The respondent gives verbal consent to participate at the beginning of the interview.

Data Handling

An important part of maintaining respondent confidentiality is the careful handling and storage of data. Steps taken by BLS, CHRR, and NORC to ensure the confidentiality of all respondents to the NLSY79 include maintaining secure networks, restricting access to geographic variables, and topcoding income and asset values.

Network security

The data that are stored and handled at each NLSY79 organization's site are done so with maximum security in place.  During data collection, transmission, and storage, password protection and encryption are used to secure the data. Standard protocols for network security are followed at each organization's site. Detailed information about these arrangements is not provided to the public to prevent anyone from circumventing these safeguards.

Restricting access to geographic information

Geographic information about NLSY79 respondents is available only to researchers who are designated agents of BLS. These researchers must agree in writing to adhere to the BLS confidentiality policy, and their projects must further the mission of BLS and the NLSY79 program to conduct sound, legitimate research in the social sciences. Applicants must provide a clear statement of their research methodology and objectives and explain how the geographic variables are necessary to meet those objectives. For more information about applying to use the restricted-use Geocode data is available on the BLS Restricted Data Access page.

Topcoding of income and asset variables

Another step taken to ensure the confidentiality of NLSY79 respondents who have unusually high income and asset values is to "topcode" those values in NLSY79 data sets. Values that exceed a certain level are recoded so that they do not exceed the specified level. In each survey round, income and asset variables that include high values are identified for topcoding. For example, the wage and salary income variable usually is topcoded, but variables indicating the amount received from public assistance programs are not. Notes in the codebooks for topcoded income and asset variables provide more information about the exact calculations used to topcode each variable. For more information see the NLSY79 Documentation section.

References

Center for Human Resource Research. "Technical Sampling Report Addendum: Standard Errors and Deft Factors for Rounds IV through XIV." Columbus, OH: CHRR, The Ohio State University, 1994.

Frankel, M.R.; Williams, H.A.; and Spencer, B.D. Technical Sampling Report, National Longitudinal Survey of Labor Force Behavior. Chicago: NORC, University of Chicago, 1983.

Baker, Paula C.; Mott, Frank L.; Keck, Canada K.; and Quinlan, Stephen V. NLSY79 Child Handbook: A Guide to the 1986-1990 NLSY79 Child Data. Columbus, OH:  CHRR, The Ohio State University, 1993.

NORC. NLSY-National Longitudinal Survey of Labor Force Behavior Interviewer's Manual-Household Screening. Chicago: NORC, University of Chicago, 1978.

Olsen, Randall J. "The Effects of Computer Assisted Interviewing on Data Quality." Columbus, OH: CHRR, The Ohio State University, 1991.

• Household Interview Section for NLSY79 Round 29 Questionnaire

• Migration History and Family Background Section for NLSY79 Round 29 Questionnaire

• Marital History Section for NLSY79 Round 29 Questionnaire

• Military Section for NLSY79 Round 29 Questionnaire

• On Jobs Section for NLSY79 Round 29 Questionnaire

• Employer Supplement Section for NLSY79 Round 29 Questionnaire

• Business Ownership Section for NLSY79 Round 29 Questionnaire

• Business Match Section for NLSY79 Round 29 Questionnaire

• Gaps Section for NLSY79 Round 29 Questionnaire

• Training Section for NLSY79 Round 29 Questionnaire

• Spouse Labor Information Section for NLSY79 Round 29 Questionnaire

• Fertility Section for NLSY79 Round 29 Questionnaire

• Health Section for NLSY79 Round 29 Questionnaire

• Income, Recipiency, Debt, and Assets Section for NLSY79 Round 29 Questionnaire

• Interview End Section for NLSY79 Round 29 Questionnaire

• Locator Section for NLSY79 Round 29 Questionnaire

• Interview Remarks Section for NLSY79 Round 29 Questionnaire

• Household Interview Section for Round 28 Questionnaire

• Migration History Family Background Section for Round 28 Questionnaire

• Marital History Section for Round 28 Questionnaire

• Regular Schooling Section for Round 28 Questionnaire

• Military Section for Round 28 Questionnaire

• On Jobs Section for Round 28 Questionnaire

• Employer Supplement Section for Round 28 Questionnaire

• Business Ownership Section for Round 28 Questionnaire

• Business Match Section for Round 28 Questionnaire

• Gaps Section for Round 28 Questionnaire

• Training Section for Round 28 Questionnaire

• Spouse Labor Information Section for Round 28 Questionnaire

• Fertility Section for Round 28 Questionnaire

• Health Section for Round 28 Questionnaire

• Smoking and Alcohol Use Section for Round 28 Questionnaire

• Income and Recipiency Section for Round 28 Questionnaire

• Attitudes and Personality Section for Round 28 Questionnaire

• Retirement Expectations Section for Round 28 Questionnaire

• Wills Section for Round 28 Questionnaire

• Foreclosure Section for Round 28 Questionnaire

• Financial Literacy Section for Round 28 Questionnaire

• Interview End Section for Round 28 Questionnaire

• Locator Section for Round 28 Questionnaire

• Interviewer Remarks Section for Round 28 Questionnaire

• Retention vs response rate
• Reasons for non-intervie w (RNI)