Gilpin 2007.

Methods	Cohort study Baseline survey: cohort 1 ‐ 1993; cohort 2 ‐ 1996 Follow‐up: 3 and 6 years (cohort 1 ‐ 1996 and 1999; cohort 2 ‐ 1999 and 2002) Site: California, USA Research Question: Does receptivity to tobacco advertising and promotions during adolescents predict smoking 6 years later? Analysis: Multivariate logistic regression used to predict what factors cause smoking initiation. Control variables: gender, age, race, school performance, family smoking, and peer smoking.
Participants	3687 and 4139 adolescents, aged 12‐15 years, who were not established smokers at baseline in cohort 1 and 2 respectively. At follow‐up 1,734 (47.0%) and 1,983 (47.9%) completed all interviews in cohort 1 and 2, respectively (aged 18‐21 at 6‐year follow‐up). Survey method: telephone interviews
Interventions	High receptivity was defined as having or being prepared to use a tobacco promotional item. With the remaining respondents: Minimal receptivity was defined as adolescents who could not name a brand to the questions “think back to the cigarette advertisements you have recently seen on billboards or in magazines. What brand of cigarettes was advertised?” Low receptivity was defined as adolescents who named a brand of cigarettes they had recently seen advertised but could not name a favourite brand in response to the following question, “what is the name of the cigarette brand of your favourite cigarette advertisement” Moderate receptivity was defined as adolescents who could name a brand most advertising and could name their favourite cigarette brand
Outcomes	Adolescents categorized at each interview as committed never smokers, susceptible never smokers, experimenters, established smokers, or current established smokers. Main outcome variable of regression analysis was odds of being an established smoker at follow up. Established smoker was defined as someone who answered yes to having smoked at least 100 cigarettes in his/her lifetime.
Notes	Sample was weighted to account for household selection probabilities, differences in adolescent response levels, and loss to follow‐up. Probability of response at follow up was adjusted for demographic characteristics of parent, gender and age of adolescent, number of biological parents in the household, the smoking status of the parent, and presence of home smoking ban.