wloss data frame: center loss 1 A 12.4 2 A 10.7 3 A 11.9 4 A 11.0 5 A 12.4 6 A 12.3 7 A 13.0 8 A 12.5 9 A 11.2 10 A 13.1 11 B 9.1 12 B 11.5 13 B 11.3 14 B 9.7 15 B 13.2 16 B 10.7 17 B 10.6 18 B 11.3 19 B 11.1 20 B 11.7 21 C 8.5 22 C 11.6 23 C 10.2 24 C 10.9 25 C 9.0 26 C 9.6 27 C 9.9 28 C 11.3 29 C 10.5 30 C 11.2 31 D 8.7 32 D 9.3 33 D 8.2 34 D 8.3 35 D 9.0 36 D 9.4 37 D 9.2 38 D 12.2 39 D 8.5 40 D 9.9 41 E 12.7 42 E 13.2 43 E 11.8 44 E 11.9 45 E 12.2 46 E 11.2 47 E 13.7 48 E 11.8 49 E 11.5 50 E 11.7 Classical ANOVA summary: Df Sum Sq Mean Sq F value Pr(>F) center 4 59.879 14.9698 15.069 6.876e-08 *** Residuals 45 44.704 0.9934 --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 Pairwise comparisons using t tests with pooled SD data: loss and center A B C D B 0.2549 - - - C 0.0024 0.9938 - - D 1.4e-06 0.0029 0.2984 - E 1.0000 0.1322 0.0010 5.5e-07 P value adjustment method: bonferroni with_dummy data frame dummy_a dummy_b dummy_c dummy_e loss 1 1 0 0 0 12.4 2 1 0 0 0 10.7 3 1 0 0 0 11.9 4 1 0 0 0 11.0 5 1 0 0 0 12.4 6 1 0 0 0 12.3 7 1 0 0 0 13.0 8 1 0 0 0 12.5 9 1 0 0 0 11.2 10 1 0 0 0 13.1 11 0 1 0 0 9.1 12 0 1 0 0 11.5 13 0 1 0 0 11.3 14 0 1 0 0 9.7 15 0 1 0 0 13.2 16 0 1 0 0 10.7 17 0 1 0 0 10.6 18 0 1 0 0 11.3 19 0 1 0 0 11.1 20 0 1 0 0 11.7 21 0 0 1 0 8.5 22 0 0 1 0 11.6 23 0 0 1 0 10.2 24 0 0 1 0 10.9 25 0 0 1 0 9.0 26 0 0 1 0 9.6 27 0 0 1 0 9.9 28 0 0 1 0 11.3 29 0 0 1 0 10.5 30 0 0 1 0 11.2 31 0 0 0 0 8.7 32 0 0 0 0 9.3 33 0 0 0 0 8.2 34 0 0 0 0 8.3 35 0 0 0 0 9.0 36 0 0 0 0 9.4 37 0 0 0 0 9.2 38 0 0 0 0 12.2 39 0 0 0 0 8.5 40 0 0 0 0 9.9 41 0 0 0 1 12.7 42 0 0 0 1 13.2 43 0 0 0 1 11.8 44 0 0 0 1 11.9 45 0 0 0 1 12.2 46 0 0 0 1 11.2 47 0 0 0 1 13.7 48 0 0 0 1 11.8 49 0 0 0 1 11.5 50 0 0 0 1 11.7 Regression model with dummy variables Call: lm(formula = loss ~ dummy_a + dummy_b + dummy_c + dummy_e, data = with_dummy) Residuals: Min 1Q Median 3Q Max -1.9200 -0.6450 -0.0200 0.5175 2.9300 Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 9.2700 0.3152 29.411 < 2e-16 *** dummy_a 2.7800 0.4457 6.237 1.39e-07 *** dummy_b 1.7500 0.4457 3.926 0.000293 *** dummy_c 1.0000 0.4457 2.243 0.029835 * dummy_e 2.9000 0.4457 6.506 5.52e-08 *** --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 Residual standard error: 0.9967 on 45 degrees of freedom Multiple R-squared: 0.5726, Adjusted R-squared: 0.5346 F-statistic: 15.07 on 4 and 45 DF, p-value: 6.876e-08