Two-Way Layout with Multiple Replications per Cell Data X(i,q,j) where 1 le i le nn Subjects or Blocks 1 le q le cc Replications for (i,j) combination 1 le j le kk Treatments or Treatment Groups Example: Test for consistency across 4 laboratories for amounts of niacin detected in enriched bran flakes. Each laboratory tests 3 samples of bran flakes for each of 3 levels of known additional enrichment (0mg, 4mg, 8mg per 100g) Data source: Campbell and Pelletier (1962) See Table 7.20 in text (p331) Data by blocks: Lab1 Lab2 Lab3 Lab4 0mg: 7.58 7.87 7.71| 8.00 8.27 8.00| 7.60 7.30 7.82| 8.03 7.35 7.66 4mg: 11.63 11.87 11.40|12.20 11.70 11.80|11.04 11.50 11.49|11.50 10.10 11.70 8mg: 15.00 15.92 15.58|16.60 16.40 15.90|15.87 15.91 16.28|15.10 14.80 15.70 Within-block ranks by blocks: Lab1 Lab2 Lab3 Lab4 0mg: 3.0 8.0 6.0 | 9.5 12.0 9.5 | 4.0 1.0 7.0 |11.0 2.0 5.0 4mg: 7.0 11.0 3.0 |12.0 8.5 10.0 | 2.0 5.5 4.0 | 5.5 1.0 8.5 8mg: 2.0 9.0 4.0 |12.0 11.0 7.0 | 6.0 8.0 10.0 | 3.0 1.0 5.0 Summaries by treatment group: Xavg Ranksum Rankavg Lab1: 11.62 53.0 5.889 Lab2: 12.10 91.5 10.167 Lab3: 11.65 47.5 5.278 Lab4: 11.33 42.0 4.667 Lscore = Sum ranksum^2 for permutation test: 15201.5 Large-sample approximation: MS=12.9274 Pval=0.00480 (df=3) Carrying out Nsims=100000 Friedman-like permutations: Initializing the random-number generator at 12345678 Lscore = Sum of Squares over Treatment Groups of Treatment-Group Rank Sums: Observed Lscore=15201.5 Number of simulations with values >= Lscore and total number: 226 100000 95% CI for true P-value bracketing estimate of true pvalue: (Since Lscore >= 0, P-values are inherently two-sided.) (0.00197 0.00226 0.00255) Rank-sum (and rank-average) differences between pairs of treatments and pairwise P-values multiple-comparison-corrected for all pairs: Based on maximum pairwise rank-sum differences in N=100000 simulations Lab1 v Lab2: 38.50 4.278 5148/100000 = 0.0515 Lab1 v Lab3: 5.50 0.611 98663/100000 = 0.9866 Lab1 v Lab4: 11.00 1.222 90079/100000 = 0.9008 Lab2 v Lab3: 44.00 4.889 1568/100000 = 0.0157 Lab2 v Lab4: 49.50 5.500 373/100000 = 0.0037 Lab3 v Lab4: 5.50 0.611 98663/100000 = 0.9866 Labs 1,3,4 appear similar. Lab2 differs from Labs 1,3,4 but the difference is MCC significant only for Lab2 v Labs 3,4