Drug Usage: An Experimental Comparison of Three Assessment Conditions

66 Ss were randomly assigned to one of three drug usage assessment conditions: anonymous group-administered questionnaires, anonymous interviews, and interviews in which S‘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 Ss may substantially minimize their drug-taking activity, much descriptive and experimental drug abuse research may be quite invalid.