The smoking rate for ninth-grade students fell from 33.4 percent in 1997 to 27.6 percent in 1999. The CDC said that fewer than 5 percent of U.S. schools follow guidelines for implementing programs that could prevent or delay smoking among 20 to 40 percent of adolescents. YRBS measures the prevalence of health risk behaviors among adolescents through representative biennial national, state, and local surveys. Lifetime smoking was defined as having ever smoked cigarettes, even one or two puffs. Data were weighted to provide national estimates.
Quadratic trends suggest a significant but nonlinear trend in the data over time.
A simultaneous quadratic trend was identified for students overall, suggesting a leveling or possible decline in current smoking. The male, black, black male, and 9th-grade student subgroups also showed this simultaneous quadratic trend. In 1991, white students were 2.5 times more likely than black students and 1.2 times more likely than Hispanic students to report current smoking. In 1999, white students were 2.0 times more likely than black students and 1.2 times more likely than Hispanic students to report current smoking. Among Hispanic female students, the prevalence of frequent smoking remained stable from 1991 to 1999.