A sports psychologist investigated the effect of a pre-performance visualization routine on the number of serving errors made by junior tennis players during a match.
She conducted a field experiment using a sample of 12 junior tennis players. For Week 1, players recorded the number of serving errors they made during their practice matches without using the visualization routine. For Week 2, players were taught the routine and instructed to use it before every serve during their practice matches. The data is presented below:
| Player | Number of serving errors during practice matches in one week | |
|---|---|---|
| Without visualization routine | With visualization routine | |
| A | 18 | 15 |
| B | 24 | 20 |
| C | 15 | 11 |
| D | 30 | 22 |
| E | 21 | 18 |
| F | 35 | 21 |
| G | 12 | 10 |
| H | 28 | 24 |
| I | 16 | 16 |
| J | 22 | 18 |
| K | 40 | 32 |
| L | 14 | 15 |
The number of serving errors made by Player F was lower during the week with the visualization routine than in the week without the visualization routine. Calculate this reduction as a percentage. Show your workings.
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.