A psychologist investigates how often adults use public libraries. The same written questionnaire is delivered to 250 households in each of two neighbourhoods. Respondents report the number of times they visited a public library during the previous three months.
| Neighbourhood | Questionnaires delivered | Questionnaires returned | Mean visits among respondents |
|---|---|---|---|
| Bramley | 250 | 175 | 4.0 |
| Kingsford | 250 | 50 | 7.0 |
The psychologist then contacts 20 people in each neighbourhood who did not return the questionnaire.
| Neighbourhood | Non-respondents contacted | Mean visits among contacted non-respondents |
|---|---|---|
| Bramley | 20 | 3.8 |
| Kingsford | 20 | 1.5 |
The psychologist concludes that adults in Kingsford use public libraries more often than adults in Bramley.
Explain how the information about the non-respondents could change the comparison between the two neighbourhoods and the psychologist's conclusion.
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.