Wilkinson et al. BMC Public Health 2012, 12:332 http://www.biomedcentral.com/1471-2458/12/332 reflected not meeting public health recommendations for physical activity [28]. Physical activity reported in PE was excluded because fewer than 10% of schools nationwide require PE on a daily basis [29] and the length of time engaging in physical activity while in PE is limited [30]. Statistical analyses We calculated the frequencies of each categorical variable and the mean and standard deviation of each continuous variable. We conducted Pearson’s χ2 tests to examine the associations between the categorical variables and both cigarette experimentation and physical activity and Student’s t-tests to examine mean differences on the continuous variables by levels of the behaviors (Table 1). We examined mean differences in the demographic characteristics, acculturation, and both behaviors for each of the sensation seeking subscales using analysis of variance (ANOVA) (Tables 2 and 3). Finally, to examine relationships between the sensation seeking subscales, gender, and both behaviors, at different levels of acculturation we completed unconditional logistic regres- sion analyses stratified by level of acculturation (Tables 4 and 5). In all six regression models, we controlled for age, country of birth, and household SES. Results The prevalence of experimenting with cigarettes and meeting physical activity recommendations by the covariates is presented in Table 1. Overall, 23.3% of all parti- cipants had experimented with cigarettes. This proportion, however, differed significantly by gender, as 16.4% of girls, compared to 30.4% of boys have experimented with cigarettes (p <0.001). Cigarette experimentation steadily increases by age. Only 8.2% of youth 13 and younger reported having experimented, whereas for youth 16 and older, this proportion rose to 41.7% (p < 0.001). Significant differences in cigarette experimentation were not detected by country of birth, parental education, or level of linguistic acculturation. However, experimenters reported higher levels of sensation seeking tendencies on all three subscales compared to participants who have not experimented with cigarettes (p < 0.001 for all). Overall, only 29.0% of the youth reported being physically active for at least 60 min- utes per day on 5 or more days of the week. More boys (37.1%) met physical activity recommendations compared to girls (21.0%; p < 0.001). The proportion of participants that met physical activity recommendations did not differ significantly by age, country of birth, or parental education, but did differ by level of linguistic acculturation (p = 0.018). Participants who reported meeting physical activity recommendations reported higher levels of TAS and social disinhibition (p < 0.001 for both) compared to those that did not meet guidelines. Page 4 of 11 In Table 2 we present means and standard deviations for the sensation seeking subscales by demographic characteristics, acculturation, cigarette experimentation and physical activity for the girls. Among girls, as age increases, so did social disinhibition and DAA, but not TAS. US-born girls reported being slightly less socially inhibited than Mexican-born girls (p < 0.05). Girls whose parents had less than a high school education reported lower TAS tendencies (p < 0.05) and being more socially inhibited (p < 0.01) than girls whose parents had a high school diploma or more education. As linguistic acculturation increases among girls, so did sensation seeking tendencies on all three scales (p < 0.05 for all). As expected, girls who have experimented with cigarettes reported higher levels of TAS (6.88 vs. 5.45; p < 0.001), social disinhibition (4.35 vs. 2.71; p < 0.001) and DAA (2.25 vs. 0.67; p < 0.001) when compared to girls who have not experimented. Physical activity was not significantly associated with sensation seeking tendencies in girls. In Table 3 we present means and standard deviations for the sensation seeking subscales by demographic characteristics, acculturation, cigarette experimentation and physical activity for the boys. Overall, boys have higher levels of sensation seeking tendencies than girls (p < 0.001 for all three subscales, data not shown). Increasing age was associated with higher levels of sensation seeking tendencies on all three subscales (p < 0.05 for all). Among boys, country of birth was associated with social disinhibition (p = 0.039) only. Parental education was associated only with TAS; boys with the most educated parents having the highest levels (p = 0.018). Linguistic acculturation was related to social disinhibition (p < 0.001) but neither TAS nor DAA; boys with the highest acculturation reported being the least inhibited. As with girls, boys who have experimented with cigarettes report higher levels of sensation seeking tendencies on all three subscales: TAS (8.80 compared to 7.70; p = 0.001), Social disinhibition (4.35 compared to 3.32; p < 0.001) and DAA (2.28 compared to 0.98; p < 0.001). However, unlike for girls, meeting physical activity recommendations was associated with higher scores for both TAS (8.68 compared to 7.65; p < 0.001) and social disinhibition (3.91 compared to 3.47; p < 0.01) among the boys. In Table 4 we present the results from the logistic regression models for cigarette experimentation stratified on level of acculturation. After adjusting for age, country of birth, SES, and sensation seeking, boys were more likely to experiment with cigarettes than girls among youth in the lowest and medium levels of acculturation only (ORlowest acculturation = 2.30; 95% CI: 1.19–4.44; ORmedium acculturation = 1.95; 95% CI: 1.12–3.37). Higher levels of sensation seeking tendencies associated with DAA were significantly associated with cigarette experimentation,