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II. Data Collection Methodology

The data collection method used in the NHSDA is to conduct in-person interviews with sample persons, incorporating procedures that would be likely to maximize respondents' cooperation and willingness to report honestly about their illicit drug use behavior. Introductory letters are sent to sampled addresses, followed by an interviewer visit. A five-minute screening procedure involves listing all household members along with their basic demographic data and possible selection of sample person(s). This selection process is designed to provide the necessary sample sizes for specified population groups by selecting either 0, 1, or 2 persons per household, depending on the composition of the household.

Interviewers attempt to conduct interviews in a private place, away from other household members. The interview averages about an hour, and includes a combination of interviewer-administered and self-administered questions. With this procedure, the answers to sensitive questions (such as those on illicit drug use) are recorded by the respondent and not seen or reviewed by the interviewer. After these answer sheets are completed, they are placed by the respondent in an envelope, which is sealed and mailed to the contractor, Research Triangle Institute, with no personal identifying information attached.

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This page was last updated on June 16, 2008.