Incorporation of clustering effects for the Wilcoxon rank sum test: A large-sample approach
Incorporation of clustering effects for the Wilcoxon rank sum test: A large-sample approach
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DOI：
10.1111/j.0006-341x.2003.00125.x
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发表时间：
2003-12-01
期刊：
影响因子：
1.9
通讯作者：
Lee, MLT
中科院分区：
文献类型：
--
作者：
Rosner, B;Glynn, RJ;Lee, MLT
在统计实践中，当基础分布远离正态分布或事先未知时，经常使用Wilcoxon秩和检验来比较位置度量。普通秩和检验的一个假设是各个抽样单位是独立的。在许多眼科临床试验中，早期治疗糖尿病视网膜病变评分(ETDRS)是衡量糖尿病视网膜病变程度的主要指标。这是一个序数表，考虑Wilcoxon秩和检验来比较不同治疗组之间的糖尿病视网膜病变水平是很自然的。然而，在这种设计下，与通常的Wilcoxon秩和检验不同，受试者是随机单位，但眼睛是分析单位。此外，一个人往往会有不同的，但相关的，ETDRS评分的另一只眼睛。因此，我们建议对Wilcoxon秩和统计量的方差进行修正，该统计量解释了聚类效应，并且可以用于平衡(每个聚类的子单元数量相同)或不平衡(每个聚类的子单元数量不同)数据，无论是否存在关联，p值都进行了相应的调整。在这篇文章中，我们介绍了这一测试过程的大样本理论和模拟结果，并将其应用于索比尼视网膜病变试验中I型糖尿病患者的糖尿病视网膜病变数据。
The Wilcoxon rank sum test is frequently used in statistical practice for the comparison of measures of location when the underlying distributions are far from normal or not known in advance. An assumption of the ordinary rank sum test is that individual sampling units are independent. In many ophthalmologic clinical trials, the Early Treatment for Diabetic Retinopathy Scale (ETDRS) is a principal endpoint used for measuring the level of diabetic retinopathy. This is an ordinal scale, and it is natural to consider the Wilcoxon rank sum test for the comparison of the level of diabetic retinopathy between treatment groups. However, under this design, unlike the usual Wilcoxon rank sum test, the subject is the unit of randomization, but the eye is the unit of analysis. Furthermore, a person will tend to have different, but correlated, ETDRS scores for fellow eyes. Thus, we propose a correction to the variance of the Wilcoxon rank sum statistic that accounts for clustering effects and that can be used for both balanced (same number of subunits per cluster) or unbalanced (different number of subunits per cluster) data, both in the presence or absence of ties, with p-value adjusted accordingly. In this article, we present large-sample theory and simulation results for this test procedure and apply it to diabetic retinopathy data from type I diabetics in the Sorbinil Retinopathy Trial.