Dictionary > Wilcoxon rank-sum test

Wilcoxon rank-sum test

Definition
noun
A non-parametric test of two samples which support exclusively on the order of observations in which the two samples fall and this is an alternative option of the parametric two sample t-test.
Supplement
This test can be used to assess the null hypothesis of two populations that contains the same continuous distributions.
There are assumptions that need to consider in using this test such as; that all observations from both groups are independent, the response must be ordinal, in the alternative hypothesis the probability of an observations from one population must exceeds from the second population which is not equal to 0.5 and under null hypothesis the distributions of both groups must be equal so that the probability of an observation from one population should exceed the observation from second population or vice versa, thus there is a symmetry between populations with respect to the probability of random sampling from a large population.
Under more strict assumptions, if the responses are assumed to be continuous and the alternative is restricted the significance of W is hard to interpret, yet it can be assessed using Hodges-Lehman estimate of the difference in central tendency between two populations differs from zero.
Compare:
• Paired Samples t-test
Related terms:
• Wilcoxon Signed-rank test
• Two Sample t-test
See also:
• Mann-Whitney U test
• Hodges-Lehman estimate


You will also like...

Gene Pool and Speciation
The Gene Pool and Population Genetics

According to Charles Darwin's theory of natural selection, preferable genes are favored by nature in the gene pool, and ..

Human Reproduction
Human Reproduction

Humans are capable of only one mode of reproduction, i.e. sexual reproduction. Haploid sex cells (gametes) are produced ..

Plant Water Regulation
Plant Water Regulation

Plants need to regulate water in order to stay upright and structurally stable. Find out the different evolutionary adap..

Freshwater Ecology
Freshwater Ecology

Freshwater ecology focuses on the relations of aquatic organisms to their freshwater habitats. There are two forms of co..

Mātauranga Māori and Science Collaboration
Mātauranga Māori and Science

Mātauranga Māori is the living knowledge system of the indigenous people of New Zealand, including the relationships t..

Hormone Production
Hormone Production

Hormones are chemical messengers produced by specialized glands and they were produced by switching on the genes designe..