NLSY79

PUBLICATION 5-1: JUNE 15, 1970, SPECIFICATIONS FOR STATES AND OUTLYING AREAS OF THE UNITED STATES

FIPS 5-1 Supersedes FIPS 5 November 1, 1963

• Introduction
• Table 1. States of the United States
• Table 2. Outlying Areas of the United States

Introduction

1. Name of Standard. States and Outlying Areas of the United States.
2. Category of Standard. Fedearl General Data Standard, Representations and Codes.
3. Explanation. This standard provides names, abbreviations and codes for representing the 50 States, the District of Columbia, and the outlying areas, all of which are considered to be "first order subdivisions" of the United States.
4. Qualifications. In the application of this standard, any of the three forms of representation (i.e., names, abbreviations, or codes) may be used to represent those data elements having values (data items) of States or outlying areas of the United States. Names and abbreviations are preferred when human considerations and input reliability are important. The two character numeric code may be used in those applications where machine and numeric sorting considerations are more important, since a sort on the numeric code arranges the States in alphabetical sequence. The codes from FIPS 10, Countries, Dependencies, and Areas of Special Sovereignty, are listed in this standard for the outlying areas of the United States. The form of representation used (i.e., names, abbreviations, or codes) should be identified in format descriptions when data are interchanged.
5. Special Information. Changes in this revision of the standard are noted by an asterisk in the left margin. Also the number of changes which have occurred to an item since its original publication is noted by a superscript character following the code. All changes are explained by footnotes.
6. Specifications. See following tables.

Note: In addition to the FIPS county codes, the following codes were used when the place name was not specific enough or the place name could not be found:

TABLE 2: Outlying areas of the United States with their assigned codes

U.S. Government Printing Office: 1970 O-397-525

The country codes include the coding used in the PAPI (Paper and Pencil Interview) and the CAPI (Computer Assisted Personal Interview) interviews.

1979-1992 PAPI-Collected Coding

1993-2006 CAPI-Collected Coding

• General Information
• CDC National Vital Statistics System, 113 List
• Modified ICD-9 Codes
• Modified V Codes
• Modified E Codes
• Codes for Parts of Body in Health-related data
• National Death Index (NDI) Data

General Information on Health Codes

Health Conditions Related to Work Limitations (1979-2000)

The health sections of the NLSY79 surveys for most interview years between 1979-2000 elicited reports of health problems that limited the amount or kind of work the respondent could do. These health problems are coded using a modified version of the International Classification of Diseases (ICD-9) codes taken from the World Health Organization, International Classification of Diseases, Ninth Revision, 2 vols., WHO, Geneva, 1977 (vol. 1) and 1978 (vol. 2).

The health consolidation codes present in 1979, 1981 and 1982 represent the most complete description possible of the respondent's main cause of limitation in work gathered from a reading of the whole health section. They were also coded using the modified ICD-9 codes after the rest of the health section has been coded. The health consolidation codes, thus, represent the (proximal) description of the respondent's main cause of limitation in work, and not an underlying cause (remote) preceding the current complaint.

As originally coded, the untruncated NLSY79 health codes corresponded to the ICD-9 codes with the decimal point deleted, except for the supplemental V and E ICD-9 codes. The supplemental ICD-9 codes were modified by dropping the alpha code and adding the remaining numeric portion of the supplemental codes to a larger number. The following numeric conversion was made for the supplemental codes: V codes = 10000+ and E codes = 11000+. (Zero (0) means no health problem). The changes were necessary because alphas are not used as variable values in the NLSY79 data. These ICD-9 codes have then been collapsed further by truncating them by one digit.

A link to the ICD-9 is included below. The NLSY79 modified codes can be tracked back to general disease classifications in the ICD-9 scheme. The supplemental E and V codes and the medical terms associated with them appear in Tables 2-3 below. For more detail, see the International Classification of Diseases, Ninth Revision.

40+, 50+ and 60+ Biological Parent and Respondent Health Conditions (1998-2020)

With the addition of the 40+ Health Module in 1998, questions collecting health conditions for the biological parents of respondents have been asked of the appropriate cohort each round. This has continued with the subsequent 50+ and 60+ Health Modules. In the 50+ and 60+ Health Modules, respondents also have had the opportunity to report any other information they wanted to about their own health. 

The major health conditions of respondents’ biological parents collected in the 40+, 50+ and 60+ Health Modules are coded using the CDC, National Vital Statistics System 113 List, contained in Table 1 below. These are taken from the National Vital Statistics Reports, Volume 65, no 2 (2/16/2016), and can be found online on the CDC website.

Parts of Body Affected by Work-Limiting Health Conditions and Reported Cancer (1979-2018)

A set of numeric codes for parts of the body was developed by NORC for the 1979-1981 health sections. These codes are contained in Table 4. They have been used to code parts of the body affected by work-related injuries/illnesses mentioned above. Additionally, respondents have been asked to report cancer diagnoses and parts of the body affected by these cancers in the 40+, 50+ and 60+ Health Modules. The same codes have been applied to parts of the body affected by cancer.

National Death Index (NDI) Data

The round 29 (2020) data release contains information regarding cause, dates and location of death for deceased respondents for whom a matching death certificate was returned from an NDI search. Most of these variables are limited to the geocode and zipcode releases. Data for a subset of NLSY79 respondents was submitted for an NDI search. The subset included respondents identified as deceased during survey field periods and respondents who have proven difficult to locate or have not been interviewed for a period of time with no confirmation of their status. In order to maximize the possibility of an NDI death certificate match, multiple submissions were made for individual respondents whenever possible. These multiple submissions could include elements such as maiden names, different married names, nicknames and various multiple ethnicities reported by the respondent, any of which might appear in various combinations on a death certificate. Individual respondent records, interviewer notes and administrative data were examined in conjunction with NDI search results to determine those for which valid matches could be established. Related variables are found in the NDI VERIFICATION area of interest. Table 1 below depicts the coding scheme used for the underlying cause of death, found on the 2020 public data release. See also the Health section for information on NDI-related variables.

Table 1: CDC – National Vital Statistics System 113 List (A conversion crosswalk from the ICD-10 health codes and the National Vital Statistics System 113 List codes can be accessed in the file ICD-10 to National Vital Statistics 113 List Crosswalk (XLSX).

Modified ICD-9 Codes

The ICD-9 can be found on the CDC website as well as through many other online resources.  With the exception of the E and V codes (see tables below), the truncated codes contained in the NLSY79 data for health conditions affecting ability to work map directly to general disease classifications in the ICD-9 codes.

OTHER CERTIFICATE CODES (Section 14, Q.08, 1979)

• Codes 001-025
• Codes 026-050
• Codes 051-075
• Codes 076-100
• Codes 101-125
• Codes 126-150
• Codes 151-175
• Codes 176-200
• Codes 201-225
• Codes 226-250
• Codes 251-269
• Codes 270-290

Note: * Codes 98, 162, and 270-290 are not documented. They should be considered code 4, OTHER.

OTHER KINDS OF TRAINING CODES
(Page 135, Section 14, Q.06A, 1979)

• Codes 01-25
• Codes 26-50
• Codes 51-75
• Codes 76-96

CODES FOR MAJOR FIELDS OF STUDY AND SUBSPECIALTIES

• 0000 None, General Studies
• 0100 Agriculture and Natural Resources
• 0200 Architecture and Environmental Design
• 0300 Area Studies
• 0400 Biological Sciences
• 0500 Business and Management
• 0600 Communications
• 0700 Computer and Information Sciences
• 0800 Education
• 0900 Engineering
• 1000 Fine and Applied Arts
• 1100 Foreign Languages
• 1200 Health Professions
• 1300 Home Economics
• 1400 Law
• 1500 Letters
• 1600 Library Science
• 1700 Mathematics
• 1800 Military Sciences
• 1900 Physical Sciences
• 2000 Psychology
• 2100 Public Affairs and Services
• 2200 Social Sciences
• 2300 Theology
• 4900 Interdisciplinary Studies

This attachment contains the following PDF files of sets of Industry and Occupation code schemes:

1970 Census 3-Digit Industry and Occupation Codes (PDF). All occupations and industries (except military occupational specialties) are coded with 1970 codes. This is the main set of codes.

1980 Census 3-Digit Industry and Occupation Codes (PDF). Beginning with the 1982 survey the respondent's current or last job only is coded with the 1980 codes in addition to the 1970 codes.

2000 Census 3-Digit Industry and Occupation Codes (PDF). The 2000 Census codes were used to code industry and occupation for all jobs in the 2002 NLSY79 survey. Census published slightly revised codes in 2002, and these revised codes were used to code all jobs in the 2004 survey. Census issued another revision in 2003, and these codes were used for the 2006 survey. This attachment lists the 2000 codes, followed by the 2002 and 2003 codes; the 2002 tables note the slight differences from the 2000 list.

1977 Department of Defense 3-Digit Enlisted Occupational Classification System (PDF). All military occupational specialties collected in the military section are coded with this scheme.

• Codebooks
• Codebook supplements and other technical documentation
• Error updates

This section describes these three primary components of the NLSY79 codebook system and discusses the important types of information found within each. An additional codebook supplement exists for the Geocode data file.

Codebooks

The codebook is the principal element of the NLSY79 documentation system and contains information intended to be complete and self-explanatory for each variable in a data file. The software accompanying the NLSY79 data sets allows easy access to each variable's codebook information and permits the user to print a codebook extract for preselected variables.

Every variable is presented within the NLSY79 documentation as a block of information called a "codeblock." Each codeblock entry depicts the following important information:

• reference number
• variable title
• coding information
• frequency distribution
• location within the data file
• reference to the questionnaire item or source of the variable
• information on the derivation of created variables

Users will find that NLSY79 CAPI codeblocks present greater detail on each variable, including universe totals, universe skip patterns, and range of acceptable values information. Each of these terms is described more completely below. Codeblocks for many variables include special notes containing additional information designed to assist in the accurate use of data from that variable.

Codebooks are arranged in reference number order. As a general rule, raw questionnaire items appear first for a given survey year, followed by items from such instruments as the Information Sheet and Employer Supplement. Variables from the main body of the questionnaire are followed by created or constructed variables drawn from an external data source, such as the County & City Data Book.

Beginning with the 1993 CAPI surveys, questions relating to each job/employer, which were formerly located within the unique Employer Supplements, are merged with the main questionnaire items. A comparison of the reference number assignments used for the 1988 PAPI and 1993 CAPI variables appear in Tables 1 and provide users with a sample set of reference numbers. Users should note that not all survey year assignments will be ordered in precisely this manner.

The following figures give users an example of codebook pages before (Figure 1) and after (Figure 2) CAPI implementation.

Coding Information. Each codeblock entry presents the set of legitimate codes that a variable may assume along with a text entry describing the codes.

Dichotomous (or variables answered yes/no) are uniformly coded "Yes" = 1, "No" = 0. Other dichotomous variables have frequently been reformulated so this convention may be followed.

Discrete (Categorical), as in the case of the NLSY79 example, the variable 'Activity Most of Survey Week CPS Item'.

• WORKING
• WITH A JOB, NOT AT WORK
• LOOKING FOR WORK
• KEEPING HOUSE
• GOING TO SCHOOL
• UNABLE TO WORK
• OTHER

Continuous (Quantitative), as in the case of hourly rate of pay in the example above. These variables have continuous data but are presented in the codebook using a convenient frequency distribution. NLSY79 users will note that most valid data are positive numbers. Special cases are flagged by negative numbers in the NLSY79. See Appendix 13: Intro to CAPI Questionnaires and Codebooks in the NLSY79 Codebook Supplement for more detail on the handling of negative numbers in the data files. The following conventions have been used throughout the data:

• Noninterview -5
• Valid Skip -4
• Invalid Skip -3
• Don't Know -2
• Refusal -1

Frequency Distribution. In the case of discrete (categorical) variables, frequency counts are normally shown in the first column to the left of the code categories. In the case of continuous (quantitative) variables, a distribution of the variable is presented using a convenient class interval. The format of these distributions varies.

Derivations. The decision rules employed in the creation of main file constructed variables have been included, whenever possible, in the codebook under the title "DERIVATIONS." This information enables researchers to determine whether available constructs are appropriate to their needs. In the case of the example NLSY79 variable in Figure 1, no derivation is shown because these variables are picked up directly from the interview schedule. Certain variables will contain a reference to an appendix for the decision rules that were used in creating the variable.

Questionnaire Item. "Questionnaire item" is a generic term identifying the printed source of data for a given variable. A questionnaire item may be a question, a check item, or an interviewer's reference item appearing within one of the survey instruments.

The questionnaire location for NLSY79 entries appears either in parentheses or brackets directly after the reference number, for example R04434. (SO6D1314). The five questionnaire item numbering conventions used in the codebook are described in the Survey Instruments section (see especially Table 2).

Before the adoption of CAPI if an NLSY79 variable was not taken directly from one of the survey instruments, the questionnaire location contained an asterisk (*) in the codebook. The following categories of variables had no questionnaire numbers:

1. assigned identification numbers for the respondent, child, or family unit;
2. all derived or constructed variables;
3. variables from the following special surveys: Profiles (ASVAB), the School Survey, and the Transcript Survey;
4. variables found on constructed data files such as the Supplemental Fertility File (area of interest "Fertility and Relationship History/Created"); and
5. variables drawn from an external data source such as those found on the Geocode files.

In CAPI years, survey staff assign a question name that is not used in the questionnaire. This name remains the same in subsequent rounds, so similar created variables can be easily located.

Section, deck, and question numbers have been somewhat arbitrarily assigned to the information and questions found in special survey instruments such as the Household Screener, Information Sheet, Children's Record Forms, Household Interview Forms, and the Employer Supplements. The section and deck numbers for these special survey items were numbered sequentially after the main survey items and their specific order varies each year. The exception to this is the assignment of the deck numbers for the Employer Supplements. Question numbering is discussed earlier in the Survey Instruments section (see especially Table 3).

Universe Information. Universe information was attached to select 1979-92 variables. Beginning with the 1993 CAPI interviews, the amount of universe information was expanded to include:

1. Universe Totals: Two totals are presented:
   • the sum of the frequency counts for each coding category is presented below the individual codes; and
   • the sum of the valid responses plus missing response counts of "refusals," "don't knows," and "invalid skips" can be found in the TOTAL==========> field. The number of respondents who legitimately did not respond to a question, that is, "valid skips (-4)" and "noninterviews (-5)," are also depicted.

2. Universe Skip Patterns: The following detailed universe information will enable researchers to easily trace the flow of respondents both backward and forward through various parts of the CAPI questionnaire items included in the codebook:

   "Go to Reference # XXXXX.," appended to certain coding categories, indicates that respondents selecting that answer category were routed to the next question specified.

   "Lead In(s) Reference # XXXXX." identifies the question or questions immediately preceding the codeblock question through which the universe of respondents was routed. Each lead-in reference number is followed by the relevant response value indicators, (Default), (ALL), [1:1], [1:6], and so forth. For example:

   • R41000. (All) This means that all cases where R41000. is asked will branch to the current question. This does not imply all respondents are asked question R41000.
   • R41000. (Default) This means that the default path of control from question R41000. is to branch to the current question, but there may be conditions under which a different path would be taken.
   • R41000. [1:6] This means that whenever the response category for question R41000. takes on the values one to six inclusive, the next question is the current question record.

   "Default Next Question" specifies the next question that all respondents of the current codeblock will be asked unless some other skip condition indicates otherwise.

Valid Values Range. Depicted below the frequency distribution is information relating to the range of valid values for that particular distribution. "MINIMUM" indicates the smallest recorded value exclusive of "NA" and "DK." "MAXIMUM" indicates the largest recorded value. The computer-assisted interview contains internal range checks that limit responses to those between predesignated values, alert interviewers to verify unusual values, and bolster the information provided by the traditional minimum and maximum fields (see, for example, Figure 2 above).

• Maximum and Minimum Fields. The MIN and MAX fields define the range, that is, the lower limit and the upper limit, of data values for a given question. A MAX of $156,359 on an income question, for example, means that this value was the highest value recorded.
• Hardmax and Hardmin Fields. Hard Maximum and Hard Minimum fields denote the highest and lowest values that were accepted by the CAPI program. A Hardmax of 500,000 and a Hardmin of 0 on an income question indicate that no values above $500,000 or values lower than zero (no income) can be accepted. Dates, such as month/day/year of the respondent's last interview [lintdate] and current interview [curdate], are used as Hardmin and Hardmax values in order to restrict responses to certain questions to values within that range. Responses outside this range must be entered by the interviewer in the comment field.
• Softmax and Softmin Fields. Softmax and Softmin fields cover ranges where an answer may exceed reasonable limits yet remain within the absolute limits and are acceptable after verification. A Softmax set to $80,000 on an income question will cause the machine to "beep" and a warning to appear on the screen. Interviewers are thus alerted that the value is unusual and the respondent's answer should be verified.
• Restricted Income Values. Confidentiality issues restrict release of all income values. To insure respondent confidentiality, the values of income variables exceeding particular limits are truncated and the upper limits converted to a set maximum value.
  1. From 1979 through 1984, the upper limit on income variables was $75,000, and any amounts exceeding $75,000 were converted to $75,001
  2. Beginning in 1985, the upper limit on income amounts was increased to $100,000 due to inflation and the advancing age of the cohort, and amounts exceeding $100,000 were converted to $100,001
  3. Beginning in 1996, the top two percent of respondents with valid values were averaged and that average value replaced all values in the top range
• Users should be aware of these changes in the income ceiling if they are carrying out longitudinal analyses with these data. Upward trends in mean income statistics may reflect this change in the ceiling value. More information about truncation is available in the Income section.
• Restricted Asset Values. Confidentiality issues also restrict release of all asset values. To insure respondent confidentiality, the values of asset variables exceeding particular limits are truncated and the upper limits converted to a set maximum value. The asset amounts have different upper limits, and the types of variables and limits for those variables are as follows:
  1. Starting in 1985 all mortgage, market value of residential property, debt on residential property, miscellaneous debt and total market value of assets worth more than $150,000 were converted to $150,001; the market value and debt on a farm or business and savings that was worth more than $500,000 was converted to $500,001; the market value and debt on vehicles that was more than $30,000 was converted to $30,001
  2. Beginning in 1989, the amounts exceeding the upper limits mentioned above were assigned the average value of all values exceeding the limits, in an effort to more accurately reflect the true range of income and asset values
  3. Beginning in 1996, the top two percent of respondents with valid values were averaged and that average value replaced all values in the top range
• Users should be aware of these changes in the asset ceiling if they are carrying out longitudinal analyses with these data. Upward trends in mean asset statistics may reflect this change in the ceiling value. More information about truncation is available in the "Assets" section of this guide.

Verbatim. Generally during the PAPI years, when a NLSY79 variable was taken directly from the questionnaire, the verbatim of the question appeared beneath the variable title. If a question is the source for more than one variable, the first variable contains the verbatim while subsequent variables prompt the user to refer back to the variable containing the verbatim. The following verbatim responses appear for reference numbers R03194. and R03195. and demonstrate this convention.

• R03194. 'In Which Months of 1979 Did You (or Your Husband/Wife) Receive Supplemental Security Income? January 80 INT'
• R03195. 'See R (3194.) February'

Codebook supplements and other technical documentation

The Other Documentation section of the website includes several items that provide additional information about the NLSY79 survey. There are two NLSY79 codebook supplements. The first supplement, the NLSY79 Codebook Supplement, contains a series of attachments and appendices, variable creation procedures, supplementary coding categories, and derivations for selected variables on the main NLSY79 data files. Information provided within this document is not available in the NLSY79 codebooks, nor will it be found on the documentation files on the NLSY79 data sets. The other supplement contains comparable information specific to the NLSY79 Geocode data files. The Technical Sampling Report describes the selection of the NLSY79 sample and provides additional statistical information. Finally, the School & Transcript Surveys Documentation provides technical information about those special data collections.

Error updates

Prior to working with an NLSY79 data file, users should make every effort to acquire information on current data or documentation errors. A variety of methods are used to notify users of errors in the data files or documentation and to provide those persons who acquired an NLSY79 data set directly from the Center for Human Resource Research with corrected information.

When data errors are discovered within the data file, the correction is made and the date file is updated. These updated files then become the default files on NLS Investigator. NLSY79 Errata notices can be found in "Other Documentation" section.