Methodological issues in measuring alcohol use.

Various methodological issues influence the measurement of alcohol consumption in surveys. One factor is the reference period for which questions are asked--that is, whether respondents are asked for an exact recall of their intake during a short, recent period or for a summary of their drinking behavior over a longer period, such as the past year. Longer recall periods provide sufficient time to link consumption data with concurrently collected data on the prevalence of alcohol-related outcomes. Another factor influencing survey results is the approach used to measure alcohol consumption. Two commonly used measures are the usual quantity/frequency (QF) and graduated frequency (GF) approaches, both of which allow researchers to estimate the volume of alcohol intake. Other issues that researchers conducting surveys should consider include the use of beverage-specific versus overall questions, open-ended versus categorical responses, and measurement of standard versus actual drink sizes. Finally, features of the overall survey design--such as the mode of interview (i.e., in person versus by telephone), the use of computerized survey instruments, and measures to ensure confidentiality--influence the reliability and validity of the data.