NLSY79 Appendix 17: Interviewer Characteristics Data

National Longitudinal Survey of Youth - 1979 Cohort

NLSY79 Appendix 17: Interviewer Characteristics Data


Interviewer Characteristics Data

Many researchers are interested in knowing if or how much interviewers affect respondent's answers. To enable researchers to investigate these questions all NLSY79 data releases since 1988 have contained information on each interviewer's characteristics. From 1979-2000, information on the characteristics of NLSY79 interviewers primarily comes from the National Opinion Research Center's (NORC) interviewer personnel files. Data from the 2002-present  surveys come from forms filled in by each interviewer during their NLSY79 training program.

The majority of NLSY79 surveys have the following variables available: interviewer ID number, number of times this interviewer has previously interviewed the respondent, the interviewer's race, the interviewer's sex, the interviewer's age, the interviewer's educational level, the amount of time the interviewer has worked at NORC, the languages other than English spoken by the interviewer, a flag identifying if the interviewer was ever terminated and the last known pay rate (in U.S. dollars per hour) for the interviewer. For the surveys run from 1981 to 1985 two additional variables are available; the number of NORC surveys the interviewer worked on during the calendar year and the number of hours spent interviewing during the calendar year. In the 2002 survey one additional variable is available; number of hours spent on the NLSY79 interview project.

Researchers should note that CHRR has built all of these variables from three snapshots of the interviewer characteristics data, plus the surveys filled out prior to the 2002-2010 interview rounds. The primary snapshot reflects interviewer data a few months prior to the fielding of the NLSY79 1994 survey. Hence, changes in items like an interviewer's educational attainment or pay rate over time are not reflected in the data.

Constructing the INTCHAR ID

The key variable which links the NLSY data set with the interviewer characteristics data set is the INTCHAR ID. This variable is similar but not exactly the same as the Interviewer ID variable, which has been found on the NLSY79 public use data set for many years. The INTCHAR ID is constructed from the NLSY79 Interviewer ID variable using the following steps.

First, the NLSY interviewer ID for all years prior to 1996 is divided by ten to truncate the last digit. This last digit was used to cluster interviewers together and the digit was not used in the NORC interviewer characteristics database. IDs for 1996 and 1998 do not have this last digit.

Second, each INTCHAR ID was then run through the list of all known interviewers who changed their ID. Interviewers changed their ID if they moved to different states, were promoted or demoted. Only a partial list of interviewers who changed their ID is available so there is no year when the characteristics of all interviewers are known. However, even if all the characteristics of an interviewer are not known, every effort was made to create a consistent ID number since a researcher might be interested in knowing who interviewed whom from year to year even if other information like sex is not available.

Third, for all of the surveys after 2002, all NLSY79 interviewers were given new round-specific project IDs, whether or not they had previously participated in the project. To match these interviewers, a manual search was done using the interviewers' first and last names. If a multiple match was possible because of a common last name (i.e. multiple interviewers with the last name Smith) the birth date was checked to determine a match.

The resulting ID was then used to search the NORC interviewer characteristics database. Most of the IDs match, but a small number  do not. The following table shows the number and percentage of respondents whose interviewer was found in the NORC interviewer characteristics database by survey year. Readers should note that most interviewers interviewed multiple respondents so not finding even a single interviewer in the NORC interviewer characteristics database causes dramatic changes in the number and percentage of interviewers found columns.

Two years (1979 and 1987) have large numbers of interviewers who were not found in the NORC interviewer characteristics database. 1979 has a large number because the database was not started until 1980. Any interviewer who worked in 1979 but not in a later year was never added to the database. The 1987 interview was primarily fielded via the telephone to save money. Telephone interviewers who did not also do face-to-face interviews are not part of the  database.

Table 1. Interviewers Identified in NORC database by Survey Year

Year # of Respondents Interviewed # of Interviewers Matched
Percentage Not Matched
1979 12686 9619 24.2%
1980 12141 10946 9.8%
1981 12195 10967 10.1%
1982 12123 11400 6.0%
1983 12221 11980 2.0%
1984 12069 11585 4.0%
1985 10894 10374 4.8%
1986 10655 10119 5.0%
1987 10485 6825 34.9%
1988 10465 9394 10.2%
1989 10605 9906 6.6%
1990 10436 9321 10.7%
1991 9018 8105 10.1%
1992 9016 8480 5.9%
1993 9011 8618 4.4%
1994 8891 8701 2.1%
1996 8636 8050 6.8%
1998 8399 7649 8.9%
2000 8033 7814 2.7%
2002 7726 7657 0.1%
2004 7661 6851 10.6%
2006 7654 7328 4.3%
2008 7757 7742 0.1%
2010 7565 4422 41.6%
2012 7301 6047 17.28%
Average --- --- 9.1%
Note: For 2006 an interviewer was considered to be a match if their age could be determined.

Other Interviewer Characteristics Variables

This section describes all the other variables available beyond the Interviewer's ID.

Variables Available for Survey Years 1979-2010

Interviewer Count (INTCHAR_YRSWITHR)

This counts the number of years the interviewer has interviewed the respondent. For example if the interviewer count in 2008 contains a 4 this means that the 2008 interviewer for the respondent has already interviewed that person 4 previous times. Please note that the number of times does not include the 2008 interview. Also note the series does not look ahead into the future. If they are also interviewed by the same interviewer in 2010, this information is NOT used to update the 2008 number. All 1979 values are zero, since no one has been previously interviewed.

Interviewer Race (INTCHAR_RACE)

-3 = missing

Interviewer Sex (INTCHAR_SEX)

1 = MALE
-3 = missing

Interviewer Age (INTCHAR_AGE)

Age of the interviewer in the interview year.
-3 = missing

Interviewer Education (INTCHAR_EDUCATION)

1 = Grade 0-8
2 = Grade 9-11
3 = High School Graduate
4 = Vocational degree
5 = Some College
6 = College Graduate
7 = Graduate School
8 = Masters Degree
9 = Professional Degree
0 = Other

Interviewer Tenure (INTCHAR_TENURE)

Number of years spent working at NORC as of interview year. 0 means less than half a year.

Variables Available for Survey Years 1979-2000

Interviewer Languages (INTCHAR_LANG1, INTCHAR_LANG2)


Interviewer Last Pay Rate at time database received from NORC. (INTCHAR_OUTPAY)

1 = $3.00 to $5.00 per hour
2 = $5.01 to $7.50
3 = $7.51 to $10.00
4 = $10.01 to $15.00
5 = $15.01 and up
-3 = Pay Rate Not In database

Variables Available for Survey Years 1979-1996

Interviewer Type of Termination (INTCHAR_TERMINATE)

0 = Never Left NORC
1 = TERMINATED by NORC for cause
2 = Left NORC by own choice

Variables Available for Survey Years 1981-1985


Number of Hours Worked on NORC projects in calendar year


Number of NORC surveys/projects worked on in calendar year

Available for Survey Year 2002 Only


Hours spent in 2002 on the NLSY79 main, child and young adult surveys.
-3 = missing.