Compare 2 or more percentages
Are percentages in each category the same?
Nonparametric Approach. Contingency table test (or Test of Proportions). See chapter 14.
Are percentages in ordered categories (low, medium, high) the same?
Nonparametric Approach. Kruskal-Wallis test. See chapters 5 and 14.
Are percentages in ordered categories (below, above) related to ordered groups (low, medium, high)?
Nonparametric Approach. Kendall's tau correlation coefficient. See chapters 8 and 14.
Chapter references are to the course textbook Statistical Methods in Water Resources.