Method

YTS data are collected from randomly selected classes of students in randomly selected public middle (grades 6-8) and high schools (grades 9-12). A weight was associated with each questionnaire to reflect the likelihood of sampling each student and to reduce bias by compensating for differing patterns of non-response. The weighted results can be used to make important inferences concerning tobacco use risk behaviors of all regular public school students in grades 6 through 8 and 9 through 12 in the state of Missouri. The YTS was conducted in Missouri in 2003 and 2005.