Related Experiment Video
Updated: Jun 28, 2026

Flypub To Study Ethanol Induced Behavioral Disinhibition and Sensitization
Published on: May 18, 2020
[The Wilcoxon, Mann and Whitney test: conditions under which and hypotheses for which it is applicable]
1Akademie der Wissenschaften der DDR, Zentralinstitut für Mikrobiologie und experimentelle Therapie Jena.
Abstract:
The test of Wilcoxon, Mann and Whitney is applicable only under the assumption that the two distribution functions FX and FY do not intersect. In case of doubt this assumption should be examined by drawing the estimates of FX and FY. If the assumption is true, the test simultaneously examines whether X and Y have equal means, equal medians, and whether 'X greater than Y' and 'Y greater than X' have the same probability 1/2. Independent of the assumption one concludes 'FX not equal to FY' in case of significance and 'P(X greater than Y) = 1/2 in case of no significance and large sample sizes. If the assumption may be violated, no statement is possible concerning means or medians. The probability P(X greater than Y) can be compared even against some p0 (being possibly different from 1/2), and a confidence interval for P(X greater than Y) can be calculated, when using the large sample modification of the test by Hilgers (1981).
Related Concept Videos
Test for Homogeneity
Kruskal-Wallis Test
Wilcoxon Signed-Ranks Test for Matched Pairs
Wilcoxon Signed-Ranks Test for Median of Single Population
Wilcoxon Rank-Sum Test
Statistical Inference Techniques in Hypothesis Testing: Parametric Versus Nonparametric Data
Parametric statistics, as the name suggests, assumes that data follow a specific distribution, often a normal distribution. This assumption enables robust hypothesis testing and estimation. Parametric methods, like the Student's t-test or Goodness-of-fit test, are frequently employed in biostatistics due to their robustness. For instance, comparing...

