EXAMPLE 14.23 Which Means Differ?

CASE 14.2 We apply the Bonferroni multiple-comparisons procedure with $\alpha =0.05$ to the data from the new-product evaluation study in Example 14.15 (pages 734–735). The value of $t^{**}$ for this procedure (from software or special tables) is 2.46. The $t$ statistic for comparing Basal with DRTA is $t_{12}=-2.99$. Because $\left|-2.99\right|$ is greater than 2.46, the value of $t^{**}$, we conclude that the DRTA method produces higher reading comprehension scores than Basal.