The prevalence rate of childhood obesity has increased rapidly worldwide. The childhood obesity epidemic is associated with many adverse health consequences in children as well as a financial burden for a nation's economy. A meta-analysis was conducted to investigate the effectiveness of school-based childhood obesity prevention programs in preventing childhood obesity. The objectives of this study were to 1) identify the most effective childhood obesity prevention programs through effect size comparison, and 2) identify important program components that affect the effectiveness of the intervention through subgroup analysis. The Comprehensive Meta-Analysis (CMA)program was used for all statistical analyses. Results of the meta-analysis demonstrated that the summary effect size was small (d = 0.039, 95% confidence interval). The schoolbased program identified in the meta-analysis as the most effective had a d value of 0.368. Subgroup analyses were performed because this meta-analysis study was heterogeneous (Q = 167.774, p = 0.001) with an I 2 value of 68.410%. The subgroup moderators were length of program duration, age of participants, nutrition, physical activity, parental involvement, specialist involvement, and theory based versus nontheory based intervention programs. Subgroup analyses demonstrated that significant differences (p < 0.05) occurred among the moderator components. Programs that targeted younger children less than ten years old and programs that were theory based were more effective. The meta-analysis study contained publication bias because the funnel plot was skewed and smaller studies were missing. To further explore the publication bias problem, Classic fail-safe N and Duval and Tweedie's trim and fill analyses were performed. Classic fail-safe N indicated that two programs were missing from the present study to achieve a non-biased result. The Duval and Tweedie's trim and fill analysis demonstrated that a small mean effect size difference was detected between the present observed studies and the unbiased effect size. The small mean effect size difference indicated that the results and the reported effect sizes in this meta-analysis study were valid.Key words: meta-analysis, school-based childhood obesity prevention, subgroup analysis ii ACKNOWLEDGEMENTS I want to take this opportunity to express my special thanks to Dr. Diane Tidwell, my major professor, who has guided me through this long dissertation writing process.She has been so patient and supportive to help me with the statistical questions regarding meta-analysis study. I want to thank her for editing not only my dissertation but also my papers. I have asked for her help numerous times, and she has never said no to me.

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