A psychologist investigates whether pupils find more spelling mistakes when they proofread while seated at a desk or while standing at a desk. One group of 20 pupils receives an 80-word passage and proofreads it while seated. Another group of 20 pupils receives a 120-word passage and proofreads it while standing. Both groups have five minutes, and the psychologist records the number of spelling mistakes each pupil finds.
Give one change to the materials that would make the comparison between the two groups fairer.
Give one reason why this change would be important when comparing the pupils' scores.
182 exam-style questions on OCR GCSE Psychology 7.1 Planning Research, covering 7.1.1 Hypotheses, 7.1.2 Variables, 7.1.3 Experimental Designs, 7.1.4 Populations and Sampling, 7.1.5 Ethical issues, and 7.1.6 Dealing with ethical issues and BPS Code. Each one has a worked solution and a mark scheme showing where the marks go.