A health psychologist conducted a study to investigate if sleeping with a lavender-scented pillow improves self-reported sleep quality compared to using a standard unscented pillow. A repeated measures design was used to test a small group of 8 participants. Each participant slept with a lavender-scented pillow for one week and a standard unscented pillow for another week (with the order counterbalanced). At the end of each week, participants rated their sleep quality on a scale from 1 (very poor) to 10 (excellent). The data obtained from the study is presented in the table below.
| Participant | Sleep quality rating (1–10) with lavender-scented pillow | Sleep quality rating (1–10) with standard unscented pillow |
|---|---|---|
| 1 | 8 | 5 |
| 2 | 9 | 7 |
| 3 | 6 | 6 |
| 4 | 7 | 4 |
| 5 | 8 | 8 |
| 6 | 9 | 5 |
| 7 | 5 | 3 |
| 8 | 8 | 6 |
What would be the appropriate non-parametric inferential statistical test to use to analyse the data from this study? Give reasons for your answer.
644 exam-style questions on OCR A Level Psychology Research methods and techniques. Each one has a worked solution and a mark scheme showing where the marks go.