Estimating under- and over-reporting of drinking in national surveys of alcohol consumption: identification of consistent biases across four English-speaking countries.

BACKGROUND AND AIMS: Questions about drinking 'yesterday' have been used to correct under-reporting of typical alcohol consumption in surveys. We use this method to explore patterns of over- and under-reporting of drinking quantity and frequency by population subgroups in four countries.
DESIGN: Multivariate linear regression analyses comparing estimates of typical quantity and frequency of alcohol consumption with and without adjustments using the yesterday method. SETTING AND PARTICIPANTS: Survey respondents in Australia (n = 26 648), Canada (n = 43 371), USA (n = 7969) and England (n = 8610). MEASUREMENTS: Estimates of typical drinking quantities and frequencies over the past year plus quantity of alcohol consumed the previous day.
FINDINGS: Typical frequency was underestimated by less frequent drinkers in each country. For example, after adjustment for design effects and age, Australian males self-reporting drinking 'less than once a month' were estimated to have in fact drunk an average of 14.70 (± 0.59) days in the past year compared with the standard assumption of 6 days (t = 50.5, P < 0.001). Drinking quantity 'yesterday' was not significantly different overall from self-reported typical quantities during the past year in Canada, the United States and England, but slightly lower in Australia (e.g. 2.66 versus 3.04 drinks, t = 20.4, P < 0.01 for women).
CONCLUSIONS: People who describe themselves as less frequent drinkers appear to under-report their drinking frequency substantially, but country and subgroup-specific corrections can be estimated. Detailed questions using the yesterday method can help correct under-reporting of quantity of drinking.