Nonparametric rank tests challenge traditional statistical methods for better accuracy.
Mathematicians have studied ranks and order statistics for a long time. In the 1940s, rank tests became important in statistics. This chapter discusses nonparametric procedures like Spearman coefficient, Wilcoxon test, Wilcoxon sum rank test, and Mann–Whitney test. Tied data can cause problems in nonparametric methods. Nonparametric tests for population variances are more robust than parametric tests based on normal assumptions.
