A psychologist finds a positive correlation between the number of hours of violent television pupils watch each week and the number of detentions they receive in a term.
Explain two reasons why the psychologist cannot conclude that watching violent television causes pupils to receive detentions.
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.