2 0 1 2 Y O U T H R I S K B E H A V I O R S U R V E Y R E S U L T S Nebraska High School Survey Sample Description Sample Description School Level - All regular public schools containing grades 9, 10, 11, or 12 were included in the sampling frame. Schools were selected systematically with probability proportional to enrollment in grades 9 through 12 using a random start. 82 schools were sampled. Class Level - All classes in a required subject or all classes meeting during a particular period of the day, depending on the school, were included in the sampling frame. Systematic equal probability sampling with a random start was used to select classes from each school that participated in the survey. Response Rates Schools - 89% 73 of the 82 sampled eligible schools participated. Students - 79% 1,900 of the 2,391 sampled students submitted questionnaires. 1,885 questionnaires were usable after data editing. Overall response rate is computed as (number of participating schools/number of eligible sampled schools) * (number of usable questionnaires/number of eligible students sampled in participating schools), rounded to the nearest integer. Overall response rate - 89% * 79% = 70% Weighting A weight has been associated with each questionnaire to reflect the likelihood of sampling each student and to reduce bias by compensating for differing patterns of nonresponse. The weight used for estimation is given by: W = W1 * W2 * f1 * f2 * f3 W1 = the inverse of the probability of selecting the school; W2 = the inverse of the probability of selecting the classroom within the school; f1 = a school-level nonresponse adjustment factor calculated by school size category (small, medium, large). The factor was calculated in terms of school enrollment instead of number of schools; f2 = a student-level nonresponse adjustment factor calculated by class; f3 = a poststratification adjustment factor calculated by gender within grade and by race/ethnicity. Use of the Weighted Results The weighted results can be used to make important inferences concerning the priority health-risk behaviors of all regular public school students in grades 9 through 12.