Who is afraid of non-normal data? Choosing between parametric and non-parametric tests

in European Journal of Endocrinology
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  • 1 Departments of Clinical Epidemiology, Leiden University Medical Centre, Leiden, The Netherlands
  • 2 Departments of Biomedical Data Sciences, Leiden University Medical Centre, Leiden, The Netherlands

Correspondence should be addressed to S le Cessie; Email: S.le_Cessie@lumc.nl
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When statistically comparing outcomes between two groups, researchers have to decide whether to use parametric methods, such as the t-test, or non-parametric methods, like the Mann–Whitney test. In endocrinology, for example, many studies compare hormone levels between groups, or at different points in time. Many papers apply non-parametric tests to compare groups. We will explain that non-parametric tests have clear drawbacks in medical research, and, that’s the good news, they are often not necessary.


     European Society of Endocrinology

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