A researcher was interested in the relationship between the number of hours of sleep restriction and cognitive performance on a driving simulator.
As part of her research, she conducted a pilot study as follows. Nine participants who were matched for their driving experience took part. Each participant was allocated a letter from A to I randomly. This determined the number of hours of sleep they were permitted the previous night and the subsequent hours they spent awake before the simulator trial. The combinations are shown in Table 1 below.
Table 1: The number of hours of sleep permitted and hours spent awake for each participant (labelled A – I)
| A | B | C | D | E | F | G | H | I | |
|---|---|---|---|---|---|---|---|---|---|
| Hours of sleep permitted | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Hours spent awake before trial | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 |
The sample used in this pilot study was an opportunity sample.
Briefly explain how using a stratified sample when the final study is conducted might be an improvement to the design.
Practise AQA A Level Psychology Scientific processes with exam-style questions for A Level Psychology. 100 questions, matched to the AQA A Level Psychology (7182) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.