European web survey on drugs: patterns of use
Most comparative drug policy analyses are underpinned by measures of drug use, often obtained from general population surveys (GPS). However, the limitations of GPS are well recognised, including the small numbers of people who use illicit drugs they include limiting the information on use patterns they can provide. Web surveys offer a potential solution to such issues. Therefore the EMCDDA conducted a project to assess the potential benefits and limitations of using web surveys for supplementing information obtained from GPS in Europe.
A questionnaire on patterns of use of cannabis (herbal and resin), amphetamines, cocaine and MDMA was administered in fourteen countries between 2016 and 2018. The questionnaire was translated from English by participant countries and each country devised its own sampling strategy. Eligible individuals were aged 18 and over, resident in the participant country, and who had used one or more of the drugs covered by the survey in the past 12 months. Participation was anonymous and voluntary.
Larger samples of users of all drug types than are found in GPS were obtained in all countries. However, there was considerable variation in both sample size and profiles of the respondents. Detailed information on patterns of use was obtained, which showed consistent patterns across countries, while price data showed good external validity.
Web surveys offer the possibility of collecting information from large numbers people who use illicit drugs quickly and cheaply and provide an opportunity to fill important gaps in our knowledge of patterns of use, particularly by recreational users. However, they also have limitations. Standardising questionnaires and approaches to data cleaning and analysis can facilitate comparisons between countries but obtaining comparable samples may be challenging. The co-operative model adopted has proved successful in balancing standardisation of methods with responsiveness to differing country contexts and needs.