17.5.2 Paired-Sample Wilcoxon Signed Rank Test

1 Introduction
2 Handling Missing Values
3 Performing paired-sample Wilcoxon Signed Rank test

Introduction

This function is used to test whether the medians of two populations are equal. This test requires input data to be matched pairs, for example, data from before and after a clinical operation. This test can be one- or two-tailed.

Unlike the paired-sample t-test, the paired-sample Wilcoxon Signed Rank test does not require the assumption that the populations are normally distributed. So when the normality is questionable, the paired sample Wilcoxon Signed Rank should be used to substitute the paired-sample t-test.

Handling Missing Values

If there are missing values in the data range, the whole pair will be excluded in the analysis

Performing paired-sample Wilcoxon Signed Rank test

Select Statistics: Nonparametric Tests: Paired-Sample Wilcoxon Signed Rank test. This opens the signrank2 dialog box.
Specify the Data Range and the desired Alternate Hypothesis.
Upon clicking OK, an analysis report sheet is generated that lists the ranks table, the degrees of freedom, the W and Z statistic, the associated p-value, and the test conclusion.