Six pupils complete a tracing task several times. The number of practice attempts and the time taken on the final attempt are shown below.
| Practice attempts | Completion time (seconds) |
|---|---|
| 1 | 82 |
| 2 | 74 |
| 3 | 69 |
| 4 | 63 |
| 5 | 58 |
| 6 | 55 |
A pupil plans to display these results as a scatter diagram. The pupil will use the title “Practice attempts and completion time”. The horizontal axis is labelled “Practice attempts”, but its evenly spaced scale runs from 0 to 3. The vertical axis is labelled “Completion time (seconds)” and has an evenly spaced scale from 0 to 90. The pupil will plot the points (1, 82), (2, 74), (3, 69), (4, 63), (5, 85) and (6, 55), then join consecutive points with straight lines.
Describe three corrections the pupil should make to the plan.
Describe the relationship shown by the corrected results and explain why the results do not show that practice caused the change in completion time.
173 exam-style questions on OCR GCSE Psychology 7.3 Analysing Research, covering 7.3.1 Types of Data, 7.3.2 Measures of central tendency, 7.3.3 Other descriptive statistics, 7.3.4 Tables, Charts and Graphs, 7.3.5 Reliability, 7.3.6 Validity and effects on validity, and 7.3.7 Sources of bias. Each one has a worked solution and a mark scheme showing where the marks go.