Comparison of three data collection methodologies for the study of young illicit drug users.

Three data collection methods (street-intercept, telephone ring-in and focus-group discussions) were compared for their feasibility, reliability, validity and cost. The subjects of investigation were drug-related behaviours, attitudes and knowledge among current illicit drug users aged 16 to 21 years in Sydney. All three methods were found to be feasible and to produce reliable and valid information. Few differences in the demographic make-up and drug-use profiles of the samples were evident. The main differences between the data collections related to cost and the type of information obtained. The street-intercept method was the cheapest per completed interview and the focus-group method was the most expensive. Focus-group discussions were considered a valuable adjunct to the surveys because they facilitated an understanding of the quantitative survey results. It was concluded that the street-intercept method is the preferred survey method because of its lower cost and lower susceptibility to volunteer bias compared to the telephone ring-in. For repeated data collection to monitor changes in drug use patterns, street-intercept surveys in combination with focus-group discussions are recommended.