Both the ERCAAP and WHO studies used a similar methodology (Cherpitel, 1989a) in which probability samples of patients 18 years and older were obtained by sampling consecutive arrivals to each ER in the study, with equal representation of each shift for each day of the week during the study period. Each patient was approached with an informed consent to participate. Completion rates for the ERCAAP studies averaged 72%, while those for the WHO studies averaged 91%. Interviewers trained in each ER setting obtained a BAC estimate, and administered a 25-minute questionnaire that included, among others items, the time of injury occurrence, drinking in the six hours prior to injury, amount consumed, and drinking following injury.
