A psychologist records the number of minutes that each adult learner spends practising sign language with another person during one week. Each learner then completes the same sign-recognition test, producing a score out of 40. On a scatter diagram, the psychologist places sign-recognition score on the horizontal axis and practice time on the vertical axis.
A student claims that sign-recognition score must therefore be the IV and practice time must be the DV.
Explain why the student's identification of the IV and DV is incorrect. Identify one extraneous variable that could account for a relationship between practice time and sign-recognition score.
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.