Measurement error in alcohol consumption: the Swiss Health Survey.

It is planned to include in the Swiss Health Survey (SHS) the questions on the consumption of alcohol that have been part of the Trend Surveys of the Swiss Institute for the Prevention of Alcohol and Drug Problems (SIPA). Since both surveys use different questioning methods (SHS: telephone interview/self-administered questionnaire; SIPA Trend Surveys: personal interviews) a comparative study was carried out to test possible effects of the methods used on responses about alcohol consumption. A split-sample design was used, whereby 1097 persons were asked about their alcohol intake by personal interview, and 1154 persons completed a self-administered questionnaire with the same questions. Considerable differences were found: on an average, consumption reported by personal interview was 38.5% higher among males (including abstainers: 35.9%) and 18.0% higher among females (including abstainers: 17.4%) than that reported by self-administered questionnaire. Consumption figures as assessed by personal interview correspond better to the per capita consumption figures as estimated by sales. Preliminary conclusions concerning the design of future surveys of alcohol consumption in Switzerland are presented.