Longitudinal studies examining stability in reports of age at drinking onset indicate that reliability is fair to poor. Using data from two panels of the National Longitudinal Survey of Youth (NLSY) collected one year apart, Prause et al. (2007) reported an intraclass correlation of 0.36 for adults and 0.19 to 0.29 for early adolescents. Bailey and colleagues (1992) found that only 27.8% of middle schoolers reported the same age at first drink one year after their first report, with over 20% reporting an age difference of 3 or more years. Results from a study conducted by Johnson and Mott (2001) that was also based on NLSY data revealed a mean absolute difference of 1.83 years in age at first alcohol use queried 2 years apart.
