Turkiye Klinikleri Journal of Biostatistics

.: ORIGINAL RESEARCH
Evaluating the Power of Meta-Analyses for Mean Differences: Methodological Research
Ortalama Farklar İçin Meta-Analizlerin Gücünün Değerlendirilmesi: Metodolojik Araştırma
Nazlı TOTİK DOĞANa, Zeliha Nazan ALPARSLANa
aDepartment of Biostatistics, Çukurova University Faculty of Medicine, Adana, Türkiye
Turkiye Klinikleri J Biostat. 2022;14(1):14-21
doi: 10.5336/biostatic.2022-88046
Article Language: EN
Full Text
ABSTRACT
 Objective: Meta-analysis is a method that summarizes the results of various independent studies on the same subject and is used to obtain more reliable and accurate results. An important issue that is a sign of quality in metaanalyses, which is at the top of the evidence pyramid, is power, and the power of a meta-analysis can be evaluated under the two model approaches: fixed effect or random effect, with the existence of heterogeneity. Despite this importance, power details are not included in many meta-analysis studies. Whatever the model, power is influenced by effect size, the smallest sample size among studies, level of heterogeneity and the number of articles included in the meta-analysis. This study aims to determine the minimum sample size for a given number of articles in order to reach an acceptable power for a meta-analysis. Material and Methods: The power values for different numbers of articles (2, 5, 7, 10, 15, 18) and minimum of sample sizes in articles were determined, taking into consideration different effect sizes (0.1-0.2, 0.3-0.4, 0.5-0.7) under fixed and random effect models of low, medium and high heterogeneity. Results: In order for a meta-analysis study with a higher heterogeneity and/or a lower effect size to reach an acceptable power, the minimum sample size in the included articles should be high. Conclusion: This study, which considers the factors affecting power, can provide guidance to clinicians on how to calculate power according to heterogeneity and what is necessary or sufficient to achieve an acceptable quality in their studies.

Keywords: Meta-analysis; power analysis; effect size; fixed effect model; random effect model
ÖZET
 Amaç: Meta-analiz, birbirinden bağımsız benzer konulardaki çalışmaları bir araya getirerek çalışmaların sonuçlarındaki çeşitliliği açıklamak, daha güvenilir ve doğru sonuçlara ulaşılmasını sağlamak amacıyla kullanılan bir yöntemdir. Kanıt değeri yüksek olan meta-analiz çalışmalarında, nitelik göstergesi olan en önemli husus güçtür ve bu güç, heterojenliğin varlığına göre sabit etki ya da rastgele etki modeli olmak üzere kullanılan iki yaklaşım altında değerlendirilir. Bu öneme rağmen birçok meta-analiz çalışmasında güç detaylarına yer verilmemektedir. Yapılan güç değerlendirmeleri etki büyüklüğü, makalelerdeki minimum örnek büyüklüğü ve çalışma sayıları faktörlerinden etkilenir. Bu çalışmada, belirli etki büyüklüğünde kabul edilebilir bir güce ulaşmak adına makalelerdeki minimum örnek büyüklüğünün ve makale sayısının belirlenmesi amaçlanmıştır. Gereç ve Yöntemler: Düşük, orta ve yüksek heterojenliğe sahip rastgele etki ve sabit etki modelleri altında farklı etki büyüklükleri (0,1-0,2, 0,3-0,4, 0,5-0,7) dikkate alınarak farklı makale sayıları (2, 5, 7, 10, 15, 18) ve makalelerdeki örnek büyüklüklerinin minimumu değerlendirilerek güç değerleri belirlenmiştir. Bulgular: Heterojenlik düzeyinin daha fazla olduğu ve/veya düşük etki büyüklüğüne sahip bir meta-analiz çalışmasına dâhil edilen makalelerdeki örnek büyüklüklerinin minimumunun yüksek olması ile ancak kabul edilebilir bir güce ulaşılabilmektedir. Sonuç: Gücü etkileyen faktörlerin göz önünde bulundurulduğu bu çalışma, heterojenlik durumuna göre nasıl güç hesabı yapılabileceği ve kabul edilebilir bir kaliteye ulaşmak adına nelerin gerekli veya yeterli olduğu konusunda klinisyenlere rehberlik sağlayabilir.

Anahtar Kelimeler: Metaanaliz; güç analizi; etki büyüklüğü; sabit etki modeli; rastgele etki modeli
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