A clinical psychologist investigated the efficacy of Trauma-Focused Cognitive Behavioural Therapy (TF-CBT) on PTSD symptom severity. She used a Wilcoxon Signed Ranks test to compare the pre-treatment and post-treatment scores of 10 patients (N=10N = 10N=10). The psychologist proposed a directional (one-tailed) hypothesis that PTSD symptom severity would decrease following the therapy.
After carrying out the test, the calculated value of T T\,T was found to be 12 (T=12T = 12T=12).
| N | Level of significance for a one-tailed test | ||
|---|---|---|---|
| 0.05 | 0.025 | 0.01 | |
| Level of significance for a two-tailed test | |||
| 0.1 | 0.05 | 0.02 | |
| N = 5 | 0 | - | - |
| 6 | 2 | 0 | - |
| 7 | 3 | 2 | 0 |
| 8 | 5 | 3 | 1 |
| 9 | 8 | 5 | 3 |
| 10 | 11 | 8 | 5 |
| 11 | 13 | 10 | 7 |
| 12 | 17 | 13 | 9 |
Explain whether these results are significant at p≤0.05 p \le 0.05\,p≤0.05 and if the research hypothesis can be accepted.
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.
