Dr Vance wanted to investigate the effectiveness of two different relapse-prevention programmes for individuals recovering from alcohol addiction after 6 months.
He sampled two groups of patients who had completed their respective recovery programmes:
Dr Vance assessed each patient's recovery status at a 6-month follow-up, classifying them as either ‘Abstinent’ or ‘Relapsed’.
| Therapy Type | Patients who remained ‘Abstinent’ | Patients who ‘Relapsed’ |
|---|---|---|
| CBT | 12 | 18 |
| MBCT | 21 | 9 |
Complete Table 2 to calculate the chi-squared statistic (χ2\chi^2χ2) for Dr Vance's data to two decimal places.
| Observed (O) | Expected (E) | O–E | (O–E)2(O–E)^2(O–E)2 | (O–E)2/E(O–E)^2 / E(O–E)2/E | ||
|---|---|---|---|---|---|---|
| CBT | ‘Abstinent’ | 12 | 16.5 | |||
| ‘Relapsed’ | 18 | 13.5 | ||||
| MBCT | ‘Abstinent’ | 21 | 16.5 | |||
| ‘Relapsed’ | 9 | 13.5 | ||||
| Chi-squared (χ2\chi^2χ2) = |
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.
