A clinical psychologist investigated the effectiveness of two interventions for post-traumatic stress disorder (PTSD): Prolonged Exposure (PE) therapy and Eye Movement Desensitization and Reprocessing (EMDR). After a 12-week course of treatment, patients' PTSD symptom severity scores (on a scale of 0 to 80) were recorded.
The psychologist calculated the standard deviation of the PTSD symptom severity scores for the PE therapy group to be 14.82.
For the EMDR group, the standard deviation of the symptom severity scores was found to be 5.13.
Interpret what these two standard deviations show about the symptom severity scores of the patients in both treatment groups.
Practise Edexcel A Level Psychology Research methods and skills with exam-style questions for A Level Psychology. 657 questions covering Research methods and skills, matched to the Edexcel A Level Psychology (9PS0) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
