Confidentiality & Informed Consent

National Longitudinal Survey of Youth - 1979 Cohort

Confidentiality & Informed Consent

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 obtaining access to geographic variables in the NLSY79, see the NLS Web site at

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 Documentation section.


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.