A researcher is interested in comparing the effectiveness of three different parts of therapy for anger problems. 8 participants are randomly assigned to 3 treatment conditions: Cognitive Therapy (CT), Cognitive-Behavioral Therapy (CBT), and Interpersonal Therapy (IT). All participants done the weekly treatment for 8 weeks. Participants take an anger test before and after the 8-week treatments. Every participant's difference score (= anger score after the treatment minus (-) anger score before the treatment) is shown in the following table. The 3 therapists in this experiment have equal educational levels and clinical experiences.
a. What statistical test should be used to examine the data?
b. Identify H0 and Ha for this study.
c. Conduct the appropriate analysis.
d. Should H0 be rejected? What should the researcher conclude?