Question

A clinical psychologist is interested in knowing if different types of treatments have an effect on the
number of flashbacks per week experienced by Iraq War veterans. She randomly selected a group of 24 veterans
with posttraumatic stress disorder (PTSD) from the local VA hospital. Each person is randomly assigned to one of
three groups: Group 1 is a waiting list control group (no treatment); Group 2 receives Eye Movement
Desensitization and Reprocessing (EMDR); and Group 3 gets cognitive-behavioral therapy (CBT). Thus, eight
people are assigned to each group. The following data are obtained:
Group 1 Group 2 Group 3
15 10 7
10 8 2
7 12 5
20 9 10
15 5 6
14 4 3
12 6 10
14 8 4
a. Describe the statistical test to be done.

b. State the null and alternative hypotheses

c. What is the critical value of the test statistic? What is the decision rule for rejecting Ho?
CV: ______________________ Reject Ho if F ≥ _________________
d. Paste in SPSS output below, circling the observed value of the test statistic. Also show your work for eta2
, and a

Tukey test, if necessary.

e. Write out an APA Style conclusion about the research project. Use the context of the study in your answer.

Answer 1

sspss output

ANOVA                      
       Sum of Squares   df   Mean Square   F   Sig.
g1   Between Groups   71.875   6   11.979   .374   .847
   Within Groups   32.000   1   32.000      
   Total   103.875   7          
g2   Between Groups   45.000   6   7.500   1.667   .532
   Within Groups   4.500   1   4.500      
   Total   49.500   7          

ANOVA                      
       Sum of Squares   df   Mean Square   F   Sig.
g1   Between Groups   95.875   6   15.979   1.997   .494
   Within Groups   8.000   1   8.000      
   Total   103.875   7          
g3   Between Groups   60.875   6   10.146   5.073   .327
   Within Groups   2.000   1   2.000      
   Total   62.875   7      

ANOVA                      
       Sum of Squares   df   Mean Square   F   Sig.
g3   Between Groups   61.875   5   12.375   24.750   .039
   Within Groups   1.000   2   .500      
   Total   62.875   7          
g2   Between Groups   29.000   5   5.800   .566   .737
   Within Groups   20.500   2   10.250      
   Total   49.500   7          

   

ANOVA                      
       Sum of Squares   df   Mean Square   F   Sig.
g1   Between Groups   71.875   6   11.979   .374   .847
   Within Groups   32.000   1   32.000      
   Total   103.875   7          
g2   Between Groups   45.000   6   7.500   1.667   .532
   Within Groups   4.500   1   4.500      
   Total   49.500   7          

ANOVA                      
       Sum of Squares   df   Mean Square   F   Sig.
g1   Between Groups   95.875   6   15.979   1.997   .494
   Within Groups   8.000   1   8.000      
   Total   103.875   7          
g3   Between Groups   60.875   6   10.146   5.073   .327
   Within Groups   2.000   1   2.000      
   Total   62.875   7      

ANOVA                      
       Sum of Squares   df   Mean Square   F   Sig.
g3   Between Groups   61.875   5   12.375   24.750   .039
   Within Groups   1.000   2   .500      
   Total   62.875   7          
g2   Between Groups   29.000   5   5.800   .566   .737
   Within Groups   20.500   2   10.250      
   Total   49.500   7