A two-factor ANOVA is conducted to evaluate the effectiveness of exposure therapy in treating civilians and combat veterans who have PTSD. Both groups of clients are randomly assigned to receive either exposure therapy or routine care. A significant interaction effect is found in the two-factor ANOVA. Which of the following interpretations is most appropriate in light of these results?
a. Exposure therapy is more effective than routine care.
b. Both routine care and exposure therapy are effective.
c. The comparative effectiveness of the two treatment conditions varies, depending upon whether the clients are civilians or combat veterans.
d. Routine care is more effective than exposure therapy.
An analysis of covariance (ANCOVA) is conducted for a study using the pretest and posttest scores of two groups. The F-ratio is statistically significant. What does this mean?
a. There is a significant difference between the two groups on the posttest scores when the effects of the pretest scores are controlled.
b. There is a significant difference between the two groups on the pretest scores when the effects of the posttest scores are controlled.
c. There are significant differences between the two groups on both the pretest and the posttest scores.
d. All of these.
A post hoc test is conducted to make multiple comparisons between the mean scores of three groups of clients in a child guidance center. Group A receives play therapy, only. Group B receives family therapy, only. Group C receives both play and family therapy. The significance level is .05 . The p value for the difference between Groups A and B is .66 . The p value for the difference between Groups A and C is .01 . The p value for the difference between Groups B and C is .01 . Which of the following interpretations is most appropriate in light of these results?
a. Play therapy and family therapy appear to be equally effective.
b. Play therapy appears to be effective.
c. Family therapy appears to be effective.
d. The combination of play and family therapy appears to be more effective than either play therapy alone or family therapy alone.
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