The document discusses non-parametric statistical tests for comparing distributions that are not normally distributed or that involve ordinal data. It specifically describes the Wilcoxon Rank-Sum test for comparing two independent samples, and provides an example comparing the medians of two emergency room operating rates. It also describes the Kruskal-Wallis test for comparing three or more independent samples, and provides an example comparing the medians of filling times across three machines.

1. Ordinal Dependent Variable or Non-normal Continuous Variable Week 14 4/6/09 Comparing non-parametric statistics Final due 4/12/09

6. Wilcoxon Rank-Sum Test: Tie in 3 rd and 4 th places Ranked Capacity values: Capacity Rank Hosp A Hosp B Hosp A Hosp B 71 1 77 2 82 3.5 82 3.5 85 5 88 6 92 7 94 8 97 9 Rank Sums: 20.5 24.5

12. Obtaining a Ranking Machine1 Machine2 Machine3 14 9 2 15 6 7 12 10 1 11 8 4 13 5 3 Raw Data Ranks 65 38 17 Machine1 Machine2 Machine3 25.40 23.40 20.00 26.31 21.80 22.20 24.10 23.50 19.75 23.74 22.75 20.60 25.10 21.60 20.40