İki İşlem Üç Periyot Dual Dengeli Çapraz Tasarımların Nesne Düşüşlerine Sağlamlığının Değerlendirilmesi

Abstract

Çapraz tasarımlar, çeşitli işlemlerin karşılaştırılması amacıyla klinik ve medikal alanlarda sıkça kullanılan popüler tasarımlardır. Bu tasarımlarda, her bir deney birimine her bir farklı zaman periyodunda bir işlem uygulanır ve her periyot sonunda deneğin yanıtı alınır. Çapraz tasarımlarda denekler (nesneler)  çalışmayı işlem sırasını tamamlamadan bıraktığında yanlı sonuçlara, deneyin istatistiksel gücünde azalmaya, hatta tasarımın temel işlem karşılaştırmalarının yapılamadığı bağlantısız tasarıma dönüşmesi gibi oldukça ciddi sorunlara neden olabilir. Bu çalışmada, ilgilenilen işlem karşılaştırmalarının denek içi ölçümlerden elde edilen farklar kullanılarak tahminini mümkün kılan iki işlem üç periyot dual dengeli tasarımların son periyot nesne düşüşleri durumunda sağlamlıkları, A optimallik kriteri kullanılarak elde edilen performans ölçüleri ve bağlantısız tasarım üretme olasılıkları incelenerek değerlendirilmiştir.

Keywords

• Çapraz tasarımlar
• Nesne düşüşü
• Sağlamlık
• Bağlantısız tasarımlar
• Dual dengeli tasarımlar

Assessing the Robustness of Two Treatments Three Periods Dual Balanced Crossover Designs to Subject Dropout

Abstract

Crossover designs are very popular designs which are frequently used in clinical and medical research to compare various treatments. In these designs, one treatment is given to each subject for each different time period and response of each subject is taken at the end of each period. When subjects withdraw from the study before they complete their treatment sequence it may cause rather serious problems such as biased results, decrease in the statistical power of study, even a conversion of the design to a disconnected design in which the basic treatment comparisons cannot be performed. In this study, the robustness of two treatments three periods dual balanced designs which enables the estimation of interested treatment comparisons using differences derived from within-subject measurements are evaluated by analyzing the performance measurements obtained by using A optimality criterion and the probability of generating a disconnected design.

Keywords

• Crossover designs
• Subject dropout
• Robustness
• Disconnected designs
• Dual balanced designs

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