Drug usage: an experimental comparison of three assessment conditions

Sixty six subjects were randomly assigned to one of 3 drug usage assessment conditions: anonymous group administered questionnaires, anonymous interviews, and interviews in which the subject's name was verified at the outset. No differences appeared in terms of expressed attitudes toward drugs and self reported use of legal drugs. In spite of promises of confidentiality, however, differences did occur when 'illegal' dependent variables were introduced. Since interviewed subjects may substantially minimize their drug taking activity, much descriptive and experimental drug abuse research may be quite invalid.