A psychologist sets up a drinks station in a controlled classroom. Participants enter one at a time and are asked to pour the amount of water they would choose to drink. Each participant receives either a 300 ml cup or a 500 ml cup. The cups are the same colour and material. The psychologist uses the same water jug and reads the same instructions to every participant.
A second psychologist repeats the investigation with new participants, following the same written instructions and equipment list. The results are shown below.
| Cup capacity | Mean volume poured in the first investigation (ml) | Mean volume poured in the repeat investigation (ml) |
|---|---|---|
| 300 ml | 181 | 179 |
| 500 ml | 246 | 249 |
Explain one strength of the laboratory method in this investigation. Use both sets of results in your answer.
139 exam-style questions on OCR GCSE Psychology 7.2 Doing Research, covering 7.2.1 Experiments, 7.2.2 Interviews, 7.2.3 Questionnaires (Surveys), 7.2.4 Observations, 7.2.5 Case Studies, and 7.2.6 Correlations. Each one has a worked solution and a mark scheme showing where the marks go.