Abstract
The aim of monitoring is to keep a finger on the pulse. In this article, we focus on a drug monitoring system (DMS): a local research system, continuously collecting data on hard drugs, drug users, and related issues. The methodology of the drug monitoring system combines qualitative and quantitative methods, i.e., community fieldwork, interviews with key informants and a bi-annual drug user survey. The system has been developed inductively: theory and methods were developed from daily practice. The present article aims to provide a scientific and methodological foundation for a DMS. We incorporated questions with respect to internal and external validity. The following strategies have been applied to meet the criteria of ‘trustworthiness’: triangulation, prolonged engagement, persistent observation, member checks, peer debriefing, negative case analyses, thick description, and reflexive journal. Methodological triangulation used in a complementary model appears to be an important tool.