Multiple Comparison with a Control for One-Way layouts Control-other comparisons with multiple-comparison correction Numbers of glucocorticoid receptor sites per Leukocyte cell for controls and 4 types of leukemia/anemia The first treatment (the control) are normal subjects. Hollander & Wolfe (Table 6.4, p201) See OneWayMultComp.txt for more detail and more analyses Grp #1 (n=14) Normal subjects (Control) Grp #2 (n= 5) Hairy-cell anemia Grp #3 (n= 6) Chronic lymphatic leukemia Grp #4 (n= 4) Chronic myelocytic leukemia Grp #5 (n= 8) Acute leukemia Data: Grp#1 Grp#2 Grp#3 Grp#4 Grp#5 3500 5710 2930 6320 3230 3500 6110 3330 6860 3880 3500 8060 3580 11400 7640 4000 8080 3880 14000 7890 4000 11400 4280 8280 4000 5120 16200 4300 18250 4500 29900 4500 4900 5200 6000 6750 8000 5 treatment groups with 37 total observations: Sample means and rank means for treatment groups: #1 (n=14): DataAv= 4760.71 RankAv= 14.43 #2 (n= 5): DataAv= 7872.00 RankAv= 26.70 #3 (n= 6): DataAv= 3853.33 RankAv= 8.42 #4 (n= 4): DataAv= 9645.00 RankAv= 28.63 #5 (n= 8): DataAv= 11908.75 RankAv= 25.31 See OneWayMultComp for a table of observations and midranks and for the Kruskal-Wallis test. MULTIPLE COMPARISONS WITH A CONTROL: Which of the k-1 non-control treatment groups are significantly LARGER than the control, allowing for multiple comparisons? (We could also ask for significantly different in absolute value, or even significantly smaller, but here we consider significantly greater.) See Section 6.7 in the text. As in OneWayMultComp.m, we use normalized Wilcoxon rank-sum differences, and base a multiple-comparison-corrected P-value for treatment #i on the number of times that the maximum of treatments #j vs. control group normalized comparisons is LARGER THAN the observed treatment #i vs control comparison. Since this is a one-sided procedure, absolute values are not used. NOTE THAT this is the method of Steel (1959) (text p259) and NOT the Nemenyi-Damico-Wolfe method discussed in most of Section 6.7. For comparison, the following are MULTIPLE-COMPARISON-UNCORRECTED P-values. One-way Wilcoxon W and Z values: #2 vs. #1: W= 80.0 E(W)= 50.0 Z= 2.788 P=0.0026 (1-sided, UNCORR) #3 vs. #1: W= 43.0 E(W)= 63.0 Z=-1.655 P=0.9511 (1-sided, UNCORR) #4 vs. #1: W= 63.0 E(W)= 38.0 Z= 2.667 P=0.0038 (1-sided, UNCORR) #5 vs. #1: W=121.0 E(W)= 92.0 Z= 1.984 P=0.0236 (1-sided, UNCORR) Maximum observed Z-value: 2.7885 Note that 2 have P<0.01 and 1 more have P<0.05. Simulating P-values for MULTIPLE-COMPARISON-CORRECTED comparisons for groups #2-#5 vs control: Initializing the random-number generator at 12345678 Number of permutations: 10000 One-sided MULTIPLE-COMPARISON-CORRECTED P-values: #2 vs #1: Z= 2.788 P= 53/10000 = 0.0053 #3 vs #1: Z=-1.655 P= 9995/10000 = 0.9995 #4 vs #1: Z= 2.667 P= 91/10000 = 0.0091 #5 vs #1: Z= 1.984 P= 775/10000 = 0.0775 Note that 2 have P<0.01 and 0 more have P<0.05.