Comparing probability and non-probability sampling methods in Ecstasy research: implications for the internet as a research tool.

The usage of Ecstasy and related drug (ERD) has increasingly been the focus of epidemiological and other public health-related research. One of the more promising methods is the use of the Internet as a recruitment and survey tool. However, there remain methodological concerns and questions about representativeness. Three samples of ERD users in Melbourne, Australia surveyed in 2004 are compared in terms of a number of key demographic and drug use variables. The Internet, face-to-face, and probability sampling methods appear to access similar but not identical groups of ERD users. Implications and limitations of the study are noted and future research is recommended.