An ecologist is investigating whether there is an association between the species of tree ('Oak', 'Ash', 'Beech', 'Birch') and the presence of a specific nesting bird species ('Present', 'Absent'). They collect survey data categorised into these four tree species and two nesting states.
Using the extract from the table of critical values presented below, what is the critical value for use with the Chi-square (χ2\chi^2χ2) test in this study at the 1% level of significance (p≤0.01p \le 0.01p≤0.01)?
| Degrees of freedom (dfdfdf) | 0.10 | 0.05 | 0.02 | 0.01 |
|---|---|---|---|---|
| 1 | 2.706 | 3.841 | 5.412 | 6.635 |
| 2 | 4.605 | 5.991 | 7.824 | 9.210 |
| 3 | 6.251 | 7.815 | 9.837 | 11.345 |
| 4 | 7.779 | 9.488 | 11.668 | 13.277 |
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.