Journal of Research in Didactical Sciences

Research Article

Mann-Whitney Test for Two Independent Groups

Bright Asare 1 * , Yarhands Dissou Arthur 1, Benjamin Adu Obeng 1, Sadri Alija 2, Senad Orhani 3
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1 University of Skills Training and Entrepreneurial Development (USTED), Kumasi
2 Faculty of Business and Economics, South East European University, North Macedonia
3 Faculty of Education, University of Prishtina, Prishtina
* Corresponding Author

Abstract

The Mann-Whitney U test is a popular nonparametric method used to compare two independent groups when data do not meet the assumptions required for traditional parametric tests, such as normality or equal variances. Developed by Mann and Whitney in 1947, and also known as the Wilcoxon Rank-Sum test, it works by ranking all observations from both groups and examining differences in these ranks, making it suitable for ordinal data, skewed distributions, or small sample sizes. This test is widely used in fields like education, psychology, health sciences, and social research, where real-world data often deviates from ideal conditions. Its main advantage is that it reduces the impact of outliers and extreme values, but it can be sensitive to differences in distribution shapes and may be less powerful than parametric tests when the data are actually normal. Statistical software such as SPSS, R, Python, or Jamovi allows researchers to perform the test easily, automatically calculating the U statistic, handling tied ranks, and producing p-values. Interpreting results involves looking at the median ranks, p-values, and effect sizes to understand both statistical and practical significance. Compared to parametric alternatives like the independent t-test, the Mann-Whitney U test offers a flexible and reliable way to compare two independent groups, providing meaningful insights even when data are non-normal or measured on an ordinal scale.

License

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Bibliographic Info

Journal of Research in Didactical Sciences, 2026, Volume 5, Issue 1, pp. 13-31

https://doi.org/10.51853/jorids/512

Publication date: 15 Dec 2026

Online publication date: 11 Apr 2026

Article Views: 12

Article Downloads: 10

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e-ISSN: 2997-5905