The combination of two surveys conducted in 2005 provided a sample of approximately 33,000 individuals aged 18 to 64, enabling an examination of how the data collection method affects the measurement of the prevalence of sensitive behaviors such as psychoactive substance use: the Life Events and Health (EVS) survey was conducted using a self-administered computer-assisted interview (CASI) with audio prompts via headphones, while for the 2005 Health Barometer survey, data collection was carried out using Computer-Assisted Telephone Interviewing (CATI).