*Choose Index below for a list of all words and phrases defined in this glossary.*

**Wilcoxon Mann-Whitney Test** - Used to test the null hypothesis that two populations have identical distribution functions against the alternative hypothesis that the two distribution functions differ only with respect to location (median), if at all. It does not require the assumption that the differences between the two samples are normally distributed. In many applications, it is used in place of the two sample t-test when the normality assumption is questionable. This test can also be applied when the observations in a sample of data are ranks, that is, ordinal data rather than direct measurements.

[Category=Quality ]

*Source: American Society for Quality, 31 October 2010 09:08:01, http://www.asq.org/glossary/ *

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**Mann-Whitney** - Mann-Whitney performs a hypothesis test of the equality of two population medians and calculates the corresponding point estimate and confidence interval. Use this test as a nonparametric alternative to the two-sample t-test.

[Category=Data Quality ]

*Source: iSixSigma, 03 February 2011 09:04:00, https: web.archive.org/web/20111109014246/http:www.isixsigma.com/index.php?option=com_glossary *

**Wilcoxon Rank Sum Test** - A test used in nonparametric statistics used to compare the locations of two populations, to determine if one population is shifted with respect to another. The method employed is a sum of ranks comparison.

[Category=Data Quality ]

*Source: iSixSigma, 04 March 2011 08:06:15, https: web.archive.org/web/20111109014246/http:www.isixsigma.com/index.php?option=com_glossary *

Data Quality Glossary. A free resource from GRC Data Intelligence. For comments, questions or feedback: dqglossary@grcdi.nl