Difficulties with telephone-based surveys on alcohol consumption in high-income countries: the Canadian example

Accurate information concerning alcohol consumption level and patterns is vital to formulating public health policy. The objective of this paper is to critically assess the extent to which survey design, response rate and alcohol consumption coverage obtained in random digit dialling, telephone-based surveys impact on conclusions about alcohol consumption and its patterns in the general population. Our analysis will be based on the Canadian Alcohol and Drug Use Monitoring Survey (CADUMS) 2008, a national survey intended to be representative of the general population. The conclusions of this paper are as follows: (1) ignoring people who are homeless, institutionalized and/or do not have a home phone may lead to an underestimation of the prevalence of alcohol consumption and related problems; (2) weighting of observations to population demographics may lead to a increase in the design effect, does not necessarily address the underlying selection bias, and may lead to overly influential observations; and (3) the accurate characterization of alcohol consumption patterns obtained by triangulating the data with the adult per capita consumption estimate is essential for comparative analyses and intervention planning especially when the alcohol coverage rate is low like in the CADUMS with 34%.