Rationale: Much of what is known about college drinking comes from self-report survey data. Such surveys typically ask students to indicate how many drinks they consume within a given period of time. It is currently unclear whether college students and researchers use similar operational definitions of a single drink. This information is critical given the widespread reliance on survey data for assessing the correlates and consequences of college drinking.
Objectives: This study investigated whether college students define standard drink volumes in a way that is consistent with the operational definitions commonly used by researchers.
Methods: Students (n= 106) were administered an alcohol survey and then asked to perform three tasks. The tasks involved free-pouring fluid into empty cups of different sizes and estimating the volume of a single beer, a shot of liquor, or the amount of liquor in a mixed drink. The volumes poured by students then were compared with standards used in a well-known nationwide survey (i.e., 12 oz of beer and 1.25 oz of liquor in a shot or mixed drink).
Results: In every cup size of every task, students overestimated how much fluid they should pour to create a standard drink. In all three tasks, the magnitude of the discrepancy increased with cup size. Collapsed across cup sizes, students overpoured shots by 26%, mixed drinks by 80%, and beer by 25%. When a more liberal serving size of liquor (1.5 oz) was used as the standard, the results of the mixed drink task remained unchanged. However, the volumes poured by students during the shot free-pour task differed from the standard in only one cup size.
Conclusions: The data suggest that college students drink more alcohol than indicated by their survey responses, raising questions about the validity of widely used alcohol surveys. Efforts to educate students about the alcohol content of standard drinks should be enhanced.