A psychologist wants to investigate job satisfaction among all 300 employees at a hospital. The psychologist has a complete staff list on which every employee has a different number from 1 to 300. The psychologist plans to obtain a random sample of 30 employees using the following procedure.
| Stage | Planned procedure |
|---|---|
| 1 | Set a random number generator to produce numbers from 1 to 240. |
| 2 | Generate 30 numbers, counting a number again if it is produced more than once. |
| 3 | If a selected employee refuses to take part, ask their line manager to nominate a replacement. |
After correcting the procedure, the psychologist obtains the following sample.
| Employee group | Number in the target population | Number in the sample |
|---|---|---|
| Full-time employees | 180 | 9 |
| Part-time employees | 120 | 21 |
| Total | 300 | 30 |
Describe how the psychologist should correct the planned procedure.
Using the information in the second table, explain why the psychologist should be cautious when generalising the findings to all 300 employees.
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.