Statistical Methods in Clinical Trials

Calculating the sample size in scientific studies is one of the critical issues as regards the scientific contribution of the study. The sample size critically affects the hypothesis and the study design, and there is no straightforward way of calculating the effective sample size for reaching an accurate conclusion.…

• DOĞAN YÜCEL
• MUHİTTİN ABDULKADİR SERDAR
• MURAT CİHAN

Calculating the sample size in scientific studies is one of the critical issues as regards the scientific contribution of the study. The sample size critically affects the hypothesis and the study design, and there is no straightforward way of calculating the effective sample size for reaching an accurate conclusion.…

• DOĞAN YÜCEL

Calculating the sample size in scientific studies is one of the critical issues as regards the scientific contribution of the study. The sample size critically affects the hypothesis and the study design, and there is no straightforward way of calculating the effective sample size for reaching an accurate conclusion.…

• CEYHAN CERAN SERDAR
• DOĞAN YÜCEL

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• LUKMAN THALIB

Biochemical markers have a central position in the diagnosis and management of patients in clinical medicine, and also in clinical research and drug development, also for brain disorders, such as Alzheimer's disease. The enzyme-linked immunosorbent assay (ELISA) is frequently used for measurement of low-abundance biom…

• ŞERMİN GENÇ

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• ONUR BAŞER

Reference intervals are a vital part of the information supplied by clinical laboratories to support interpretation of numerical pathology results such as are produced in clinical chemistry and hematology laboratories. The traditional method for establishing reference intervals, known as the direct approach, is based…

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Reference Intervals (RIs) and clinical decision limits (CDLs) are a vital part of the information supplied by laboratories to support the interpretation of numerical clinical pathology results. RIs describe the typical distribution of results seen in a healthy reference population while CDLs are associated with a sign…

• YEŞİM ÖZARDA

In this study, we investigate how Wilks’ lambda, Pillai’s trace, Hotelling’s trace, and Roy’s largest root test statistics can be affected when the normal and homogeneous variance assumptions of the MANOVA method are violated. In other words, in these cases, the robustness of the tests is examined. For this purpose, a…

• CAN ATEŞ
• MUSTAFA AGAH TEKİNDAL
• ÖZLEM KAYMAZ

BACKGROUND AND OBJECTIVES: In clinical trials, the relative risk or risk ratio (RR) is a mainstay of reporting of the effect magnitude for an intervention. The RR is the ratio of the probability of an outcome in an intervention group to its probability in a control group. Thus, the RR provides a measure of change in t…

In this study, Shapiro-Wilks, Lilliefors and Kolmogorov-Smirnov tests were compared for Type I error and for power of the tests. The simulation was run 100, 000 times for different situations and for different types of departures from normality. For all different sample sizes and distributions, Shapiro-Wilks gave the…

• MEHMET MENDEŞ