Department of Health and Exercise Science, University of Oklahoma, Norman, Oklahoma, USA.
J Strength Cond Res. 2013 Aug;27(8):2323-37. doi: 10.1519/JSC.0b013e318278eea0.
The statistical power, or sensitivity of an experiment, is defined as the probability of rejecting a false null hypothesis. Only 3 factors can affect statistical power: (a) the significance level (α), (b) the magnitude or size of the treatment effect (effect size), and (c) the sample size (n). Of these 3 factors, only the sample size can be manipulated by the investigator because the significance level is usually selected before the study, and the effect size is determined by the effectiveness of the treatment. Thus, selection of an appropriate sample size is one of the most important components of research design but is often misunderstood by beginning researchers. The purpose of this tutorial is to describe procedures for estimating sample size for a variety of different experimental designs that are common in strength and conditioning research. Emphasis is placed on selecting an appropriate effect size because this step fully determines sample size when power and the significance level are fixed. There are many different software packages that can be used for sample size estimation. However, I chose to describe the procedures for the GPower software package (version 3.1.4) because this software is freely downloadable and capable of estimating sample size for many of the different statistical tests used in strength and conditioning research. Furthermore, GPower provides a number of different auxiliary features that can be useful for researchers when designing studies. It is my hope that the procedures described in this article will be beneficial for researchers in the field of strength and conditioning.
实验的统计功效（或灵敏度）定义为拒绝无效零假设的概率。只有 3 个因素会影响统计功效：（a）显著水平（α），（b）处理效果的大小或幅度（效应量），和（c）样本量（n）。在这 3 个因素中，只有样本量可以由研究者操纵，因为显著水平通常在研究之前选择，而效应量由治疗的有效性决定。因此，选择适当的样本量是研究设计中最重要的组成部分之一，但常常被初学者误解。本教程的目的是描述在力量和调节研究中常见的各种不同实验设计中估算样本量的程序。重点放在选择适当的效应量上，因为当功效和显著水平固定时，这一步完全决定了样本量。有许多不同的软件包可用于样本量估计。然而，我选择描述 GPower 软件包（版本 3.1.4）的程序，因为该软件可免费下载，并能够为力量和调节研究中使用的许多不同统计检验估算样本量。此外，GPower 提供了一些对于研究人员在设计研究时非常有用的辅助功能。我希望本文描述的程序对力量和调节领域的研究人员有所帮助。
