Predicting steep escalations in alcohol use over the teenage years: age-related variations in key social influences.

Aims: This study examined how family, peer and school factors are related to different trajectories of adolescent alcohol use at key developmental periods.

Design: Latent class growth analysis was used to identify trajectories based on five waves of data (from grade 6, age 12 to grade 11, age 17), with predictors at grades 5, 7 and 9 included as covariates.

Setting: Adolescents completed surveys during school hours.

The impact of adolescent tobacco-related associative memory on smoking trajectory: an application of negative binomial regression to highly skewed longitudinal data.

Tobacco use is prevalent in adolescents and understanding factors that contribute to smoking uptake remains a critical public health priority. While there is now good support for the role of implicit (preconscious) cognitive processing in accounting for changes in drug use, these models have not been applied to tobacco use. Longitudinal analysis of smoking data presents unique problems, because these data are usually highly positively skewed (with excess zeros) and render conventional statistical tools (e.