Thirty participants aged 20 to 29 and 30 participants aged 40 to 49 are randomly assigned to one of five groups. Each group is given a list of words to recall. The lists vary in type from 1 = “most passive verbs” to 5 = “most active verbs.” The response variable is how many words can be recalled after 2 minutes. The data are given in Table 9.21.

(a) Construct a cell mean plot and comment on the apparent patterns.

(b) Construct an analysis of variance table and interpret the results.

(c) Check the assumptions by plotting the residuals against the predicted values and by conducting Levene’s test.

(d) Suppose your research is focused on how the age groups compare. Write a paragraph comparing the word recall in the two age groups. If necessary, conduct pairwise comparisons to support your statements, controlling the familywise significance level at 5%.

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Table 9.21 Data for practice exercise 2: words recalled. Verb Type 1 2 3 4 5 Age 20-29 11 12 16 12 10 11 Age 40-49 9 12 769699 MALE 522685n 12 10 16 8 11 13 14 11 16 16 16 15 13 14 9 12 9 11 11 12 14 11 10 11 14 12 14 18 15 26 20 9 17 17 8 11 20 13 14 14 18 8 15 15 85