Sargent et al. (2007, Experiment 2A) randomly divided 125 students into three groups and gave them different instructions regarding the focus of the Implicit Association Test (IAT). The dependent variable is the score on the IAT. The data is summarized in Table 6.41.

320 CHAPTER 6: Inferences for Two or More Means Table 6.41 FOCUS Black-focal White-focal Standard Mean 0.45

(a) 0.57

(b) 0.53 (ab)

Standard deviation 0.32 0.23 0.24 n (estimated) 38 39 48

(a) The letters in parentheses were provided by the authors. Means with the same letter were not significantly different. Provide a summary plot of the means, using lines to connect those that are not significantly different.

(b) Is there significant evidence that the instructions regarding focus affect the mean IAT score? Use α = 0.05.

(c) The authors state:

Although the overall difference among the 3 was not significant…planned comparisons indicated that the difference between the Black-focal and White-focal IAT was significant (t(122 ) = 2 .0 , p < .05) . . . . neither the difference between the Black-focal group and the standard IAT (t(122) = −1 .39, p = .17) nor the difference between the White-focal and the standard IAT

(t(122) = .68, p = .50 ) reached significance.

Does it appear that the authors did anything to control the experiment-wise error rate?

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