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Sample Size Estimation: A Glimpse beyond Simple Formulas¹

¹ From the Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Central Radiology Viewing Area, Room 117, 600 N Wolfe St, Baltimore, MD 21287. Received February 21, 2003; revision requested April 10; revision received July 18; accepted July 21. Address correspondence to the author (e-mail: jeng@jhmi.edu).

Small increments in the complexity of clinical studies can readily take sample size estimation and statistical power analysis beyond the capabilities of simple mathematic formulas. In this article, the method of simulation is presented as a general technique with which sample size may be calculated for complex study designs. Applications of simulation for determining sample size requirements in studies involving correlated data and comparisons of receiver operating characteristic curves are discussed.

© RSNA, 2004

Index terms: Radiology and radiologists, research • Receiver operating characteristic (ROC) curve • Statistical analysis

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