Eng John
Department of Radiology and Radiological Science, Johns Hopkins University, 600 N Wolfe St, Central Radiology Viewing Area, Rm 117, Baltimore, MD 21287, USA.
Radiology. 2003 May;227(2):309-13. doi: 10.1148/radiol.2272012051.
The number of individuals to include in a research study, the sample size of the study, is an important consideration in the design of many clinical studies. This article reviews the basic factors that determine an appropriate sample size and provides methods for its calculation in some simple, yet common, cases. Sample size is closely tied to statistical power, which is the ability of a study to enable detection of a statistically significant difference when there truly is one. A trade-off exists between a feasible sample size and adequate statistical power. Strategies for reducing the necessary sample size while maintaining a reasonable power will also be discussed.
纳入研究的个体数量，即研究的样本量，是许多临床研究设计中需要重点考虑的因素。本文回顾了决定合适样本量的基本因素，并提供了一些简单但常见情况下的计算方法。样本量与统计效能密切相关，统计效能是指当确实存在差异时，研究能够检测出统计学显著差异的能力。在可行的样本量和足够的统计效能之间存在权衡。本文还将讨论在保持合理效能的同时减少所需样本量的策略。
