A researcher investigated whether a sign above a tray-return point increased the likelihood that customers would return their trays in a community centre café. During six normal lunch sessions, the researcher either displayed the sign or did not display it. The researcher recorded the number of customers who received a tray and the number who returned it.
| Sign displayed | Session | Customers receiving a tray | Customers returning their tray |
|---|---|---|---|
| No | 1 | 44 | 20 |
| No | 2 | 63 | 31 |
| No | 3 | 78 | 37 |
| Yes | 1 | 39 | 25 |
| Yes | 2 | 55 | 37 |
| Yes | 3 | 71 | 45 |
The researcher concluded that displaying the sign increased the likelihood that a customer would return their tray.
Using the results, evaluate whether this conclusion is supported by the field experiment.
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.