Question: Posttraumatic stress disorder (PTSD) following 9/11. Levitt, Malta, Martin, Davis, and Cloitre (2007) evaluated the effectiveness of cognitive behavioral therapy (CBT) for treating PTSD and related symptoms for survivors of the 9/11 terrorist attacks on the World Trade Center (WTC). They used a pretest-posttest design to see if CBT was successful at reducing the symptoms of PTSD and related symptoms of depression. They used the Modified PTSD Symptom Scale Self-Report (MPSS-SR) questionnaire to measure symptoms of PTSD and the Beck Depression Inventory (BDI) self-report questionnaire to measure symptoms of depression. For both questionnaires, lower scores indicated fewer symptoms. The authors reported the following results: Pre- to post treatment t tests for the WTC sample revealed significant decreases in scores on the MPSS-SR, [t(3 7) = 12.7 4, p

(b) Which questionnaire (MPSS-SR or BDI) was completed by more participants?

(c) Did the authors find support for their hypothesis? Explain