Researchers conducted an investigation to determine whether there is an association between daily physical activity level and self-reported sleep quality. Participants were categorised into three activity levels (Low, Moderate, and High) and asked to rate their overall sleep quality as Poor, Average, or Excellent. The collected data is summarised in the table below:
Table 1: Sleep quality by daily physical activity level
| Activity Level | Poor | Average | Excellent |
|---|---|---|---|
| Low | 35 | 40 | 15 |
| Moderate | 20 | 55 | 35 |
| High | 10 | 25 | 45 |
Using the extract of the tables of critical values for the Chi-square test presented below, determine the critical value at the 5% probability level for the data collected in this study.
Extract of critical values for Chi-square (χ2\chi^2χ2) test:
| Degrees of freedom (df) | 0.5 | 0.05 | 0.01 |
|---|---|---|---|
| 1 | 0.455 | 3.841 | 6.635 |
| 2 | 1.386 | 5.991 | 9.210 |
| 3 | 2.366 | 7.815 | 11.345 |
| 4 | 3.357 | 9.488 | 13.277 |
| 5 | 4.351 | 11.070 | 15.086 |
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.