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 princi...

A large part of previous work dealt with the robustness of parametric significance tests against nonnormality, heteroscedasticity, or a combination of both. The behavior of tests under violations of the independence assumption received comparatively less attention. Therefore, in applications, researches may overlook that robustness and power properties of tests can vary with the sign and the ma...

SUMMARY This paper proposes the use of Wilcoxon rank sum, Wilcoxon signed rank, and sign statistics for testing certain hypotheses representing zero effects in the linear logistic regression model. A simulation study provides insight into the alternatives for which each test is most powerful. An example with rea 1 data is gi ven for each tes t.

The Wilcoxon rank-sum test is widely used to test the equality of two populations, because it makes fewer distributional assumptions than parametric procedures such as the t-test. However, the Wilcoxon rank-sum test can be used only if data are independent. When data are clustered, tests based on generalized estimating equations (GEEs) that generalize the t-test have been proposed. Here we deve...

To date, it is unknown whether waist circumference can be measured validly and reliably when a subject is in a supine position. This issue is relevant when international standards for healthy participants are applied to persons with severe intellectual, sensory, and motor disabilities. Thus, the aims of our study were (1) to determine the validity of waist circumference measurements obtained in...