Minimizing respondent attrition in longitudinal research: practical implications from a cohort study of adolescent drinking.

The methods used to maximize retention in a longitudinal study of adolescent drinking are discussed. Data were collected at three time points: at recruitment to the study, after nine months and at 18 months. Strategies to minimize attrition included the collection of detailed contact information, incentives for participation, postcard and telephone reminders and telephone interviews. Ninety-six percent of the original sample completed the first follow-up questionnaire, 92% completed the second and the study lost contact with just 3% of participants. The success of the current project is notable as this type of population is notoriously difficult to retain in longitudinal studies.