The Wilcoxon Test and Non-Null Hypotheses
G. Barrie Wetherill · Journal of the Royal Statistical Society Series B (Statistical Methodology) · 1960
SUMMARY The two-sample Wilcoxon test provides an exact test of location when the two parent populations are identical in shape. The research recorded in this paper is an investigation into the behaviour of the test, and a comparison with the behaviour of the t-test, when the two distributions differ slightly in shape.