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.
82 exam-style questions on Edexcel A Level Psychology Research methods and skills, covering Research methods and skills. Each one has a worked solution and a mark scheme showing where the marks go.