A psychologist asks 40 adults to record how many hours they spent exercising last week and to rate their own happiness on a scale from 1 (very unhappy) to 10 (very happy). She plots the pairs of scores on a scatter diagram and finds a positive correlation. A newspaper reports the study under the headline "Exercise makes you happier".
Evaluate the use of a correlation in this investigation.
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.