Spearman Rank Order Correlation and Mann-Whitney U Test
The Spearman’s Rank Order Correlation Coefficient is used to identify and test the relation between two data sets. The data, in this case, is a small sample size, or non-normally distributed. The Mann-Whitney U Test is
used to test whether two samples are derived from the same population, or whether or not the observations in one sample are larger than observations in the other. A review of the two statistical methods enables the
researcher to identify the best method to make proper inferences about a population.
The best questions answered by Mann-Whitney U Test are examining rank differences. The method has a set of assumptions that must be met before a researcher can use it to draw relationships between variables (Kendall &
Gibbons, 1990). The first assumption is that independence within the samples and mutual independence is assumed. The randomness of the sample drawn from the population is also considered (Chen & Popovich, 2002). Thirdly, ordinal and continuous measurement scales are assumed. The fourth assumption is that the two data distributions have the same shape. Mann-Whitney U Test is applicable in every field, but it is frequently
applied in healthcare, nursing, and psychology. In psychology, it is used to compare the attitude or behavior of the patient (Campbell, 2013). In medicine, it is used to compare the therapeutic effects of two drugs and
whether they are equal or not (Campbell, 2013). It can also be used to ascertain whether the medicine cures the ailment of concern or not. In the business environment, it can be used to deduce the preferences of different
people and also analyze whether these preference change depending on location.
One condition for Spearman correlation is the existence of a significant relationship between respondents to two Likert scale questions. The test does not make assumptions about data distribution, but the variables must have an ordinal, ratio, or interval scale (Puth, Neuhäuser, & Ruxton, 2015). A monotonic relationship must also exist. The test method is most relevant in determining performance in with regards to other factors such as health status and age. It can also be used to reveal the association between nurse’s academic qualification and expertise classification.
Spearman correlation and Mann-Whitney U Test are both useful quantitative techniques, but a detailed review of the two enables a researcher to identify the best method to make proper inferences about a population.
References
Campbell, M. J. (2013). Statistics at square two: understanding modern statistical applications in medicine. John Wiley & Sons.
Chen, P. Y., & Popovich, P. M. (2002). Correlation: Parametric and nonparametric measures. Thousand Oaks, CA: Sage Publications.
Kendall, M. …