Given a two-sided alpha = .05 chi-square test adjusted for clustering within high schools with an intracluster correlation of .02, a total sample size of 40 click here high schools each with an average enrollment of 150 male ST users was estimated to be needed to provide 90% power to detect a significant difference in quitting of 15% in intervention high schools to 5% in no-intervention high schools. For a high school to be eligible for inclusion in the study, it had to be located in one of 29 totally rural CA counties (a population density of 250 persons or less per square mile and no township of >50,000 persons; California State Rural Health Association, 2009). In these rural counties, there were 217 eligible high schools.

Student eligibility criteria were: male enrolled in a study high school, parental consent if 17 years of age and younger, student-signed informed assent, and reported tobacco use within the past 30 days to be considered a tobacco user. Sample selection, recruitment, informed consent, and randomization Study investigators contacted the tobacco control coordinator in the County Office of Education (COE) in each of the 29 totally rural counties (of 58 total) in CA to explain the study and to gain agreement for collaboration to recruit county high schools. Twenty-one (72.4%) of 29 counties agreed to work with study investigators to gain permission from school district superintendents and high school principals in their county by writing a letter of study support. High schools were randomly selected from a list of public high schools in these counties from the California Public Schools Directory (1993) and recruited over 4 years.

In brief, from 2000 to 2004, 41 high schools were enrolled in the study: 8 in Year 1, 15 in Year 2, 10 in Year 3, and 8 in Year 4. Investigators contacted high school principals to explain the study and gain consent for their high schools�� participation the following Fall. As a participation incentive, investigators donated $150 to each participating high school supporting their graduation dance. Schools declining to participate were replaced with another randomly selected school. The high school principal��s cover letter and study consent form were included in the students�� fall registration packets. The cover letter explained the purpose, methods, benefits, and risks of the study and provided a toll-free telephone number for parents who had questions for a study investigator.

Year 1 of the study used active parent consent, but subsequent years used passive parent consent (i.e., opt out) as detailed elsewhere (Gansky et al., 2008). Student participants provided written assent. Participating high schools, stratified on size of school and Carfilzomib enrollment year, were randomly assigned to either the intervention or the no-intervention group. Questionnaire assessment Baseline For each high school, a local person (either staff from the COE or the participating high school, i.e.