Imagine that a psychologist working with veterans with post-traumatic stress disorder wants to compare the effectiveness of several therapies focused on reducing symptoms of anxiety. The psychologist randomly sampled 20 veterans who recently returned from combat and randomly assigned each of them to receive one of four interventions for 8 weeks. A survey was used to measure the participants' anxiety at the end of the 8 weeks. Higher anxiety scores indicate more anxiety.

Anxiety scores for 5 veterans who received behavioral therapy

159

154

157

158

157

Anxiety scores for 5 veterans who received cognitive therapy

151

150

151

153

151

Anxiety scores for 5 veterans who received biofeedback therapy

155

157

154

152

156

Anxiety scores for 5 veterans who received medication therapy

156

159

155

157

158

Use SPSS to compare the mean anxiety scores with a one-way ANOVA.

1. Before computing any analyses, state the null hypothesis and alternative hypothesis in words
2. Identify the factor and dependent variable.
3. Name the levels of the factor.
4. State the degrees of freedom between groups and explain how you calculated it by hand.
5. State the degrees of freedom within groups and explain how you calculated it by hand.
6. Identify the obtained F value using SPSS and report it
7. Identify the p value using SPSS and report it
8. Explain whether the F test is statistically significant. How you know.
9. Explain what the psychologist can conclude about the relationship between different types of therapy and anxiety before conducting post hoc tests.
10. Should the psychologist conduct a post hoc test? Why or why not? If post hoc testing is needed, conduct a Tukey HSD post hoc analysis in SPSS. What does the results tell you.