Drinking with Friends: Measuring the Two-week Ecology of Drinking Behaviors.

Despite the substantial influence these acute alcohol-related problems cause globally, past research has failed historically to capture the dynamic nature of drinking events, including how multiple factors (ie, individual, group, and environmental) interact to affect event-level intoxication. Fortunately, technology (eg, transdermal alcohol monitors) and smartphone surveys have provided researchers with new avenues to measure the complex nature of alcohol consumption. This paper presents the methods of a pilot study that sought to measure event-level alcohol consumption in a natural drinking group of college students. Ten groups of friends (N=49) were followed for 2 weeks with daily diary surveys, continuous activity trackers, hourly geographic ecological momentary assessments (EMAs) on 4 separate drinking occasions, and a transdermal alcohol monitor during one group-based social event. On average, participants responded to > 75% of both daily diaries and EMAs and were compliant with activity trackers on 96% of monitoring days. Over 90% of the sample had usable transdermal data and after smoothing, peak transdermal alcohol contents ranged from 0.13 to 0.395 during the observation evening. The lessons learned during this pilot study can provide a building block for future work in this area, especially as data collection in alcohol research rapidly advances.