摘要：Objectives. Our study tested the effectiveness of network methods for identifying opinion leaders and for constructing groups. Methods. Three conditions—random, teacher, and network—were randomly assigned to 84 6th-grade classrooms within 16 schools. Pre- and postcurriculum data on mediators of tobacco use were collected from 1961 students. Peer leaders in the network condition were identified by student nominations, and those leaders were matched with the students who nominated them. Results. Students in the network condition relative to the random condition liked the prevention program more and had improved attitudes (β = −0.06; P < .01), improved self-efficacy (β = −0.10; P < .001), and decreased intention to smoke (adjusted odds ratio [OR] = 0.46; 95% confidence interval [CI] = 0.38, 0.55). Conclusions. The network method was the most effective way to structure the program. Future programs may refine this technique and use it in other settings. Smoking is the single most preventable cause of premature death and disability in the United States. 1 An estimated 430 000 deaths are attributed to cigarette smoking each year. School-based smoking and substance use prevention programs have been created to reduce this burden. 2– 9 Several reviews have shown that school-based programs can reduce tobacco use by 25% to 50%. 10– 15 Although most school-based tobacco prevention programs are based on a social-influences model, they have not been structured to take full advantage of the possible positive aspects of peer influence. One way to include social influences in school-based tobacco prevention programs is by using peer leaders. Peer-led interactive programs are hypothesized to be more effective than teacher-led programs and more effective when compared with controls. Meta-analyses of substance use prevention programs have shown that interactive programs—those that incorporate student-tostudent exercises—are more effective than lecture-style programs. 11, 14 Current guidelines for implementing school-based tobacco prevention programs recommend the use of peer leaders, 16 and a number of studies have found peer leaders to be effective implementers of tobacco prevention 17– 22 and health promotion programs. 23– 26 There is, however, considerable variation in how peer leaders are selected. Peer leaders for middle school programs have varied from college students 17, 19 to high school students 27 to students of the same age. 22, 28, 29 In some cases peer leaders are self-selected, and in other cases student nominations are used to identify same-age peer leaders. 17, 28, 30– 32 All of the school-based tobacco prevention programs that used peer leaders reported some success in reducing smoking or changing mediators. Although this evidence suggests that peer leaders are important components of health promotion programs, there have been no studies to evaluate how these leaders should be assigned to groups. In classroom settings, teachers often have students work in groups, because evidence shows that this approach improves learning. Rottier and Ogan reviewed several studies on group learning in middle and junior high schools and concluded that group learning encourages higher achievement (especially for average and belowaverage students), promotes better reasoning skills, fosters positive relationships among students, increases positive feelings toward the subject matter, and results in higher selfesteem. 33 A meta-analysis of 122 studies indicated that group learning promotes higher achievement than do individual- and competitive-learning experiences, 34 and this effect held across all ages, academic subjects, and types of learning tasks. 35– 38 Randomization is the most common method for constructing groups in classrooms. Typically, teachers ask students to count to a certain number, and students are assigned to groups with the same number. Randomization has numerous advantages, including ease of implementation, control of teacher and student biases, and objectivity. In many classrooms, teachers assign students to groups on the basis of the teachers’ knowledge of who works well with whom. Assigning students in tobacco prevention and most health promotion programs to groups on the basis of different abilities may be impractical, because it requires pairing students who engage in a behavior (smoking) with those who do not, which raises ethical concerns. We tested the effectiveness of peer leader selection strategies and group creation within a school-based tobacco prevention program. Three conditions were compared: (1) random—leaders defined as those who received the most nominations by students, and groups created by randomly assigning students to leaders; (2) teacher —leaders and groups created by teachers; and (3) network —leaders defined as those who received the most nominations by students, and groups created by assigning students to the leaders they nominated. The rationale for the network condition came from research on the effects of social-network influences on tobacco use 39– 48 and other health behaviors. 49– 52 It has been shown that peers influence tobacco use; therefore, teaching resistance skills within the context of these peer relationships is a promising approach. The network condition identifies opinion leaders through peer nominations, and it extends the logic of peer influences by matching students with the leaders that the students nominated—leaders who are 1 step (the student is assigned to a leader that the student nominated) or 2 steps (the student is assigned to a leader who was nominated by one of the student’s nominees) away. In this manner, students are assigned to the leaders they nominated, which recognizes that opinion leadership is a localized phenomenon—opinion leaders are not leaders for everyone; rather, they are leaders for those who nominate them to be leaders. 53 The 3 conditions—random, teacher, and network—each have obvious advantages and disadvantages. The random condition capitalizes on student opinions and is unbiased, but it requires the collection of network data. The teacher condition is simple to implement, because it relies on the teachers’ knowledge, but it is dependent on that knowledge alone. The network condition capitalizes on student opinions but also requires collection of network data. In addition, it requires using a computer algorithm to match the leaders with the groups. The cost of the network condition can be offset by several advantages: (1) students learn to practice resistance skills with their near peers who probably will be present in situations where smoking will occur; (2) the group process can be amplified, because students become more engaged with the curriculum; (3) curriculum lessons may continue outside the classroom, when students discuss the lessons with their friends; and (4) students may learn more if they are in a comfortable social setting with their friends. Thus, comparing the effectiveness of these conditions has important programmatic (how to implement programs in the future) and theoretical (how do programs work) implications. 54 Our study presents preliminary results from a school-based tobacco use prevention program implemented in the sixth-grade, the first year of middle school. Most of the students were aged 11 or 12 years. These ages and the corresponding grade level have been identified with the onset of smoking. 2 Two programs, a general social-influences program and a culturally tailored program, were implemented, and schools receiving these programs were compared with control schools that did not receive a specific tobacco use prevention intervention. Both programs use a social influence–based smoking-prevention curriculum for sixth-grade students, consist of 8 50-minute sessions, and include an initial session for peer leader training. Trained college-aged health educators teach the programs, usually with the regular classroom teacher in attendance. The curriculum includes Socratic discussions, role-playing, and games, and the classroom sessions take place once a week for 8 consecutive weeks. Before the programs start, peer leaders are taught how to organize their groups, how to communicate with the students, how to provide positive feedback, and how to encourage cooperation. Peer leaders distribute materials, collect materials, lead discussions, and organize group activities. In both programs, students work with their groups during every session and are asked to work on a group project outside of class. The group project—students perform skits with their assigned groups during the last session—is the culminating event of both programs. The students are given time during class to create their skits and are encouraged to work during lunchtime and after school. Both programs aim to change psychosocial mediators of tobacco use, such as attitudes toward smoking, self-efficacy, refusal skills, coping skills, and intention to smoke. Because many of the activities take place in groups, the composition of groups and the selection of leaders may be critical elements that determine program effectiveness.
