Biglan A, Severson H, Ary D, Faller C, Gallison C, Thompson R, Glasgow R, Lichtenstein E
J Behav Med. 1987 Apr;10(2):159-71. doi: 10.1007/BF00846424.
This study investigated the effects of a smoking prevention program that emphasized refusal skills training on 1730 adolescents in three high schools and six middle schools. Classes within these schools were randomly assigned to treatment or no-treatment conditions to avoid confounding schools with treatment condition. The effects of attrition on the internal and external validity of the study were examined. Although the results indicated an apparent effect of the program at the 1-year follow-up in deterring continued smoking among those who were smoking at pretest, this result may have been due to a higher rate of attrition among high-rate smokers in the treatment condition than in the control condition. Attrition also affected external validity. Across both conditions, subjects who were smoking at pretest and who were at risk to smoke were more likely to be missing at follow-up. The program did have an effect on the refusal skills of participants and the validity of this effect was not jeopardized by differential attrition.
本研究调查了一项强调拒绝技巧训练的吸烟预防计划对三所高中和六所初中的1730名青少年的影响。这些学校内的班级被随机分配到治疗组或非治疗组，以避免将学校与治疗条件混淆。研究了损耗对研究内部和外部效度的影响。尽管结果表明，在1年随访时该计划对阻止预测试时吸烟的人继续吸烟有明显效果，但这一结果可能是由于治疗组中高吸烟率者的损耗率高于对照组。损耗也影响了外部效度。在两种情况下，预测试时吸烟且有吸烟风险的受试者在随访时更有可能缺失。该计划确实对参与者的拒绝技巧有影响，且这种影响的效度并未因差异损耗而受到损害。
