example_mww - Stat 2225 Handout Example of Wilcoxon...

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Stat 2225 Handout Example of Wilcoxon Rank-Sum Test Q17.7 on p.569. Sample #1 60 66 73 75 81 Rank #1 1 2 4 5 7 Sample #2 72 78 82 90 103 Rank #2 3 6 8 9 10 H 0 : the two population locations are the same H a : the location of population 1 is to the left of the location of population 2 T 1 = 19 and T 2 = 36, n 1 = n 2 = 5; T = T 1 = 19. Based on α = 0.05, T L = 19 and T U = 36. The rejection region is therefore either T 19. Test statistic is 19 and is equal to T L . Therefore, we have enough evidence to reject H0. SGP Output: Comparison of Medians --------------------- Median of sample 1: 73.0 Median of sample 2: 83.0 Mann-Whitney (Wilcoxon) W test to compare medians Null hypothesis: median1 = median2 Alt. hypothesis: median1 < median2 Average rank of sample 1: 3.8 Average rank of sample 2: 7.2 W = 21.0 P-value = 0.0473463 Note: Make sure you know how to find the test statistic of “21” from the output. Q17.17 on p.570. Type 0: the histogram shows that it’s not reasonable to believe that the populations are from normal distribution Æ use non-parametric test.
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This note was uploaded on 01/17/2010 for the course STATS 2225 taught by Professor Li during the Spring '09 term at Langara.

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example_mww - Stat 2225 Handout Example of Wilcoxon...

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