A sports psychologist conducted a study to investigate the relationship between training method (Interval vs Continuous) and performance outcome in a 5km run (Improved vs No change). Below is a partial table of observed and expected frequencies used to calculate a Chi-square statistic.
Calculate the expected frequency for cell D. Present your answer to two decimal places and show your workings.
| Cell | Observed frequency (O) | Expected frequency (E) | O – E | (O – E)2^22 | (O – E)2^22 / E |
|---|---|---|---|---|---|
| A (Interval/Improved) | 22 | 18.28 | 3.72 | 13.84 | 0.76 |
| B (Interval/No change) | 14 | 17.72 | –3.72 | 13.84 | 0.78 |
| C (Continuous/Improved) | 11 | 14.72 | –3.72 | 13.84 | 0.94 |
| D (Continuous/No change) | 18 |
Formula for χ2\chi^2χ2:
χ2=∑(O−E)2E \chi^2 = \sum \frac{(O - E)^2}{E} χ2=∑E(O−E)2513 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.