The Wilcoxon Signed-Rank test is a nonparametric alternative to the paired-samples t test. Consider using Wilcoxon when you do not wish to make the assumptions necessary for the t test. The only assumptions made by the Wilcoxon test are that the test variable is continuous, and that the distribution of the difference scores is reasonably symmetric.

Rather than testing the hypothesis of a difference between two related medians, you may wish to test a hypothesis that implies change in a binary outcome. If so, then you should consider using the McNemar test. McNemar is designed to test the null hypothesis of no change over time or between two related samples. Unlike the Wilcoxon, the McNemar test is designed for use with nominal or ordinal test variables.