A psychologist wants to find out how motivated the 800 adult members of a leisure centre feel to exercise regularly. She obtains a sample using each of two methods.
Sample A: she asks the first 90 members who agree as they leave a weekday fitness class.
Sample B: she numbers all 800 members on the membership list and uses a random number generator to select 50.
The table shows the age groups in the target population and in each sample.
| Age group | Target population | Sample A | Sample B |
|---|---|---|---|
| 16–24 | 240 | 45 | 16 |
| 25–44 | 360 | 35 | 22 |
| 45 and over | 200 | 10 | 12 |
| Total | 800 | 90 | 50 |
Explain which sample would better support generalising the findings to all 800 members. Use the data and the sampling methods in your answer.
182 exam-style questions on OCR GCSE Psychology 7.1 Planning Research, covering 7.1.1 Hypotheses, 7.1.2 Variables, 7.1.3 Experimental Designs, 7.1.4 Populations and Sampling, 7.1.5 Ethical issues, and 7.1.6 Dealing with ethical issues and BPS Code. Each one has a worked solution and a mark scheme showing where the marks go.