Following customer feedback, a supermarket manager introduces quiet background music in the store. A psychologist compares how long shoppers stay during the week before the change and the week after it.
State the type of experiment used by the psychologist.
Give one reason for your answer to part (a).
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.