EXAMPLE 14.15 Are the Comprehension Scores Different?
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CASE 14.2 Figure 14.11 gives the summary statistics for COMP computed by SPSS. This software uses only numeric values for the factor, so we coded the groups as 1 for Basal, 2 for DRTA, and 3 for Strat. Side-by-side boxplots appear in Figure 14.12, and Figure 14.13 plots the group means. The ANOVA results generated by SPSS are given in Figure 14.14, and a Normal quantile plot of the residuals appears in Figure 14.15.
Figure 14.11: FIGURE 14.11 Summary statistics for the comprehension scores in the three groups for the new-product evaluation study of Case 14.2.
Figure 14.12: FIGURE 14.12 Side-by-side boxplots of the comprehension scores in the new-product evaluation study of Case 14.2.
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Figure 14.13: FIGURE 14.13 Comprehension score group means in the new-product evaluation study of Case 14.2.
Figure 14.14: FIGURE 14.14 SPSS analysis of variance output for the comprehension scores in the new-product evaluation study of Case 14.2.
Figure 14.15: FIGURE 14.15 Normal quantile plot of the residuals for the comprehension scores in the new-product evaluation study of Case 14.2.