Methods of testing for a deficit in single-case studies: Evaluation of statistical power by Monte Carlo simulation
Methods of testing for a deficit in single-case studies: Evaluation of statistical power by Monte Carlo simulation
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DOI：
10.1080/02643290500538372
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发表时间：
2006-09-01
影响因子：
3.4
通讯作者：
Garthwaite, Paul H.
中科院分区：
文献类型：
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作者：
Crawford, John R.;Garthwaite, Paul H.
通过比较病例与对照来检测缺陷的存在是许多神经心理学单病例研究的基本特征。蒙特卡罗模拟研究统计功率的两个竞争的方法来完成这项任务。Crawford和豪厄尔（1998;范围为44%-63%）提出的方法检测大缺损的能力较低至中等，但Mycroft、Mitchell和Kay（2002;范围为1%-13%）提出的方法检测能力极低。对偏离正态性的影响进行了检查，并对对照组和单个病例评分中不同程度的测量误差的影响进行了检查。测量误差产生了适度的减少功率时，存在于两个控制和情况下，差异更大的测量误差的影响，为单一的情况下，取决于初始水平的功率。当Mycroft等人的方法被用于测试经典解离的存在，它产生了非常高的I型错误率（范围从20.7%到49.3%）;相比之下，Crawford和Garthwaite（2005 b）提出的标准的错误率较低（范围从1.3%到6.7%）。更广泛的影响，这些结果的单例研究进行了讨论。
Testing for the presence of a deficit by comparing a case to controls is a fundamental feature of many neuropsychological single-case studies. Monte Carlo simulation was employed to study the statistical power of two competing approaches to this task. The power to detect a large deficit was low to moderate for a method proposed by Crawford and Howell (1998; ranging from 44% to 63%) but was extremely low for a method proposed by Mycroft, Mitchell, and Kay (2002; ranging from 1% to 13%). The effects of departures from normality were examined, as was the effect of varying degrees of measurement error in the scores of controls and the single case. Measurement error produced a moderate reduction in power when present in both controls and the case; the effect of differentially greater measurement error for the single case depended on the initial level of power. When Mycroft et al.'s method was used to test for the presence of a classical dissociation, it produced very high Type I error rates (ranging from 20.7% to 49.3%); in contrast, the rates for criteria proposed by Crawford and Garthwaite (2005b) were low (ranging from 1.3% to 6.7%). The broader implications of these results for single-case research are discussed.