An agricultural scientist conducted an independent measures experiment to investigate whether a new organic liquid seaweed fertilizer improves the growth of tomato plants compared to a standard synthetic nitrogen-based fertilizer. A sample of 12 tomato plants was split into two groups of 6. One group was treated with the organic seaweed fertilizer, while the other group was treated with the synthetic nitrogen fertilizer. The height increases (in cm) recorded after 4 weeks are shown below:
| Height increase (cm) with organic seaweed vs synthetic nitrogen fertilizer | |||
|---|---|---|---|
| Organic Seaweed | Synthetic Nitrogen | ||
| Plant | Height Increase (cm) | Plant | Height Increase (cm) |
| 1 | 12 | 1 | 9 |
| 2 | 15 | 2 | 13 |
| 3 | 11 | 3 | 8 |
| 4 | 14 | 4 | 11 |
| 5 | 16 | 5 | 10 |
| 6 | 10 | 6 | 7 |
Explain how you would calculate the standard deviation for each condition of this study.
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.