Learning from picture book reading. Developmental Psychology (Nov. 2006) published an article that examined toddlers’ ability to learn from reading picture books. The experiment involved 36 children at each of three different ages: 18, 24, and 30 months. The children were randomly assigned into one of three different reading book conditions: book with color photographs

(Photos), book with colored pencil drawings (Drawings), and book with no photographs or drawing (Control).

Thus, a 3 * 3 factorial experiment was employed (with age at three levels and reading book condition at three levels). After a book-reading session, the children were scored on their ability to reenact the target actions in the book. Scores ranged from 0 (low) to 3 (high). An ANOVA of the reenactment scores is summarized in the following table.

a. Fill in the missing degrees-of-freedom (df) values in the table.

b. How many treatments are investigated in this experiment?
List them.

c. Conduct a test for Age * Book interaction at a = .05.
Interpret the result practically.

d. On the basis of the test you conducted in part

c, do you need to conduct tests for Age and Book main effects?
Explain.

e. At each age level, the researchers performed multiple comparisons of the reading book condition means at a = .05. The results are summarized in the accompanying table. What can you conclude from this analysis? Support your answer with a plot of the means.

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Source df F p-value Age 11.93