Description The National Longitudinal Study of Adolescent Health (Add Health) is a school-based study of the health-related behaviors ofadolescents in grades 7-12. It has been designed to explore the causes of these behaviors, with an emphasis on the influence of social context. surveys of students, parents, and school administrators.
Waves/Rounds Wave I was conducted from September 1994 to December 1995. Wave II was conducted from April to August, 1996.
Researchers can obtain copies of Add Health instruments here.
- School administrator survey (Waves I & II)
- Adolescent in-school student survey (Wave I)
- Adolescent in-home student interview (Wave I & Wave II) (including the Add Health Picture Vocabulary Test given only in Wave I)
- Parent interview (Wave I)
- Friendship nominations and Network datasets were constructed from in-school adolescent data.
Mode of administration The School Administrator survey was a self-administered paper-and-pencil questionnaire in Wave I and was administered over the phone in Wave II. In-school student questionnaires were self-administered and later optically scanned. In-home adolescent questionnaires were administered by CAPI, as well as computer-assisted self-interview (CASI) for more sensitive questions. Parent questionnaires were administered by an interviewer on a paper-and-pencil instrument which was later scanned.
Survey lengths The in-school survey was given during one class period (ranging from 45-60 minutes). The parent questionnaire took approximately 40 minutes to complete, and the in-home adolescent questionnaire took anywhere from 60-120 minutes, depending on how many questions were on a given respondent's questionnaire. (Not all sections were administered to all respondents; adolescents were screened based on their age, gender, and past experiences so that only the appropriate questions were asked of them.) The Add Health picture vocabulary test took approximately 5 minutes.
Sample sizes A sample of 80 eligible high schools was selected. New schools were substituted for any schools which declined to participate. For each school, one of its feeder schools was also selected. 132 schools in total participated in the study (some high schools have a 7th grade; thus they serve as their own feeder schools).
All of the students in grades 7-12 in these schools were eligible to participate in the study. 90,118 in-school adolescent questionnaires were completed. A subset of eligible students (not limited to those who had completed in-school questionnaires) was selected for the in-home sample. About 5,000 participants in the in-home component had not completed an In-school Questionnaire. There were in fact several in-home subsamples; the core sample, and various over-samples, including ethnic, disabled, and sibling over-samples.
Ultimately, 20,745 in-home interviews were completed in Wave I, and 14,738 in-home interviews were completed in Wave II. (Some respondents were dropped at Wave II.) 17,713 parents answered child specific questions and 17,669 answered parent specific questions (more than one child was interviewed in some households). 164 school administrator questionnaires were returned in Wave I and 125 were completed in Wave I.
Incentives In return for their participation, schools received an unknown monetary incentive, as well as an individualized report based on their in-school data. Families did not receive incentives for their participation.
Response rates Over 70% of the schools originally selected for the survey participated. Of the adolescents sub-sampled for the in-home questionnaires, 78.9% participated in Wave I. Picture vocabulary tests are available for 95% of these (all respondents took the test, but some tests were lost in data transmission). Parent interviews are available for 85% of these respondents.
Not all of the Wave I respondents were eligible to participate in Wave II, and 65 new respondents were added to the sample. Of those eligible for participation in Wave II, 88.2% completed in-home interviews.
Data availability The Add Health data are more sensitive than many other datasets to deductive disclosure. This is due, in part, to the clustered research design. Add Health surveyed all students in grades 7 through 12 in a pair of schools in each of 80 communities in the United States. In the Add Health in-school dataset of more than 90,000 cases, a cross-tabulation of five variables can distinguish an individual record. Several hundred thousand students, family members, school staff, and others know of the participation of at least one, if not many, of respondents.
Add Health data are available in two forms--a public-use dataset and a restricted-access contractual dataset. It is a central concern of the Add Health study that the confidentiality of respondents be strictly protected. For this reason, the distribution of data will be limited in several ways: (1) public-use data includes only a subset of respondents; (2) restricted-use data will be distributed only to certified researchers who commit themselves to maintaining limited access; and, (3) in no case will identification numbers of persons nominated by the respondents be available to outside researchers.
Public-use data The public-use data contains information on Add Health's nationally representative sample of adolescents and consists of one-half of the core sample, chosen at random, and one-half of the oversample of African-American adolescents with a parent who has a college degree. Public-use datasets are distributed by Sociometrics on CD-ROM in ASCII format.
Researchers wishing to obain the public-use data, or needing more information on the public-use data should contact Sociometrics directly (not UNC Chapel Hill).Sociometrics CorporationRestricted-access data Access to the entire core sample; the special oversamples of high-education African-Americans, Chinese, Cuban, Puerto Rican, and disabled adolescents; the sample of pairs of adolescents living in the same household; both School Administrator Questionnaires, a sample of adopted adolescents, and all contextual data are available by contractual agreement with the Carolina Population Center. Contractual data are provided in separate linkable datasets and contain a hidden signature identifying the purchaser. To be eligible to enter into a contract, you must be a researcher with an IRB-approved plan for handling and storing sensitive data and sign a data-use contract agreeing to keep the data confidential.
170 State Street, Suite 260
Los Altos, California 94022-2812
In addition to an application for obtaining sensitive data, researchers must submit a $500 non-refundable fee made payable to the University of North Carolina at Chapel Hill. A copy of the contract in Adobe Acrobat file format is available to be downloaded. For further information about the contractual datasets, contact:Add Health Project*Note: the material in the sections on data availability is taken directly from the National Longitudinal Study of Adolescent Health web-site page "Datasets": http://www.cpc.unc.edu/projects/addhealth/datasets.html.
Carolina Population Center
CB#8120 University Square
Chapel Hill, NC 27516-3997
For more information about the Add Health Study contact:Joyce Tabor,
AddHealth Data Manager
Carolina Population Center
CB#8120 University Square
Chapel Hill NC 27516
Funding and Administration National Institute of Child Health and Human Development (NICHD) and 17 other federal agencies sponsored the study. NICHD contracted with the Carolina Population Center, at the University of North Carolina, Chapel Hill, and with the National Opinion Research Center at The University of Chicago. The Principal Investigator was J. Richard Udry, UNC Chapel Hill.
Addhealth web-site. Internet document: http://www.cpc.unc.edu/addhealth/
Chantala, K., Tabor, J. 1999. Strategies to Perform a Design-Based Analysis Using the Add Health Data. Carolina Population Center, University of North Carolina at Chapel Hill.
Tabor, J., personal communication. 8/21/00; 8/22/00; 8/28/00, 11/9/00.
Modi, Manisha. "National Longitudinal Study of Adolescent Health." Surveys measuring well-being. 9/14/00. Internet document: http://www.wws.princeton.edu/~kling/surveys/AddHealth.html
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