A health psychologist wanted to investigate whether dispersing lavender essential oil in a sterile workspace reduces subjective stress scores (measured on a scale of 1 to 50, with higher scores indicating higher stress) compared to an unscented workspace. She conducted a repeated measures experiment using a sample of 10 participants. Each participant completed a stressful cognitive task twice: once in an unscented room and once in a room with lavender scent diffused.
In a Wilcoxon Signed-Ranks test conducted on this data, one participant showed identical stress scores in both conditions, resulting in their data being discarded and leaving N=9N = 9N=9. The calculated value of T T\,T was determined to be 4.
Use the table of critical values for the Wilcoxon Signed-Ranks test below to answer the question.
Table: Critical values of T T\,T for the Wilcoxon Signed-Ranks test
| NNN (number of active pairs) | Two-tailed level of significance: 0.05 | Two-tailed level of significance: 0.01 |
|---|---|---|
| 8 | 4 | 1 |
| 9 | 5 | 1 |
| 10 | 8 | 3 |
Note: For significance to be shown, the calculated value of T T\,T must be equal to or less than the table (critical) value.
Write the significance statement for the analysis carried out above at a 5% significance level (p≤0.05p \le 0.05p≤0.05), assuming a non-directional (two-tailed) hypothesis.
513 exam-style questions on OCR A Level Psychology Data recording, analysis and presentation. Each one has a worked solution and a mark scheme showing where the marks go.