A researcher wanted to investigate whether there was a relationship between salivary melatonin levels and perceived sleep quality in young adults. An advert was posted on a university's online student portal asking for healthy individuals between 18 and 25 years old to take part in this research. Eight participants were recruited; they provided a saliva sample at bedtime to measure their melatonin levels (in pg/mL) and completed a questionnaire to assess their sleep quality score out of 50.
The results of the questionnaire and the saliva assays are displayed in Table 1.
| Participant number | Sleep quality score /50 | Melatonin level (pg/mL) |
|---|---|---|
| 1 | 38 | 65 |
| 2 | 15 | 22 |
| 3 | 42 | 70 |
| 4 | 20 | 30 |
| 5 | 28 | 45 |
| 6 | 12 | 18 |
| 7 | 31 | 50 |
| 8 | 45 | 78 |
Name the sampling technique that was used for this investigation.
Practise Edexcel A Level Psychology Research methods and skills with exam-style questions for A Level Psychology. 657 questions covering Research methods and skills, matched to the Edexcel A Level Psychology (9PS0) 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.
