How does sampling frame and results compare with YRBS on similar items?
Our sampling frame is similar, but not identical, to YRBS. For selecting the primary sampling units (PSUs), the population of PSUs was stratified by Census divisions. Within each Census division, the PSUs were sorted by the rural and urban and a sample was selected with probability proportional to total enrollment in grades 6 to 10. Unlike YRBS, there was no explicit stratification of PSUs by rural and urban for sampling. Within each selected school district, schools were stratified by three grade ranges: Grade 6, grades 7 and 8, grades 9 and 10. Because of differences in the wording of some questions we have not compared our data to YRBS (although this could be done). HBSC differs from YRBS in other ways such as the focus on the social and environmental context for the health behaviors and the inclusion of youth younger than those sampled in YRBS. Questions for Dr. Simons-Morton: Q: What is the correlation between tobacco, cannabis, and alcohol use? A: The correlation between tobacco
