ABSTRACT
This chapter recognizes situations that require the use of nonparametric methods and applies the sign test for sample data. It utilizes the Wilcoxon signed-rank test for small samples. The chapter applies the Mann–Whitney U test to determine if two independent samples come from identical populations. It computes Charles Edward Spearman rank correlation coefficient for ranked data. The sign test is performed when we wish to analyze two sets of data that are not gathered independently; that is, they are from the same sample. The sign test is most commonly used to test the hypothesis that the plus and minus signs are equally likely. The Mann–Whitney U test is a useful nonparametric technique that is employed in situations where the objective is to test whether two independent samples have been taken from populations with the same mean. Ranking may be as a result of inadequate units of measurement, lack of time, lack of money, or lack of adequate measuring instruments.
