The Wilcoxon-signed-rank test was proposed together with the Wilcoxon-rank-sum test in the same paper by Frank Wilcoxon in 1945 and is a nonparametric test for the one-sample location problem. The test is usually applied to the comparison of locations of two dependent samples. Other applications are also possible, e.g., to test the hypothesis that the median of a symmetrical distribution equals a given constant. As with many nonparametric tests, the distribution-free test is based on ranks.