A researcher wants to study attitudes to homework in a school of 800 students, of whom 480 are girls and 320 are boys. She uses an opportunity sample of 40 students who are in the school canteen at lunchtime. 30 of them are girls and 10 are boys.
Explain why a stratified sample would be more representative than her opportunity sample. Show your workings.
145 exam-style questions on Oxford AQA IGCSE Psychology 1.4 Research Methods, covering 1.4.1 Hypotheses, 1.4.2 Types of variables, 1.4.3 Sampling methods, 1.4.4 Strengths and weaknesses of sampling methods, 1.4.5 The experimental method, 1.4.6 Experimental designs, 1.4.7 Laboratory experiments, 1.4.8 Field and natural experiments, 1.4.9 Interviews, 1.4.10 Questionnaires, 1.4.11 Case studies, 1.4.12 Observation studies, 1.4.13 Strengths and weaknesses of research methods, 1.4.14 Correlation and scatter diagrams, 1.4.15 Strengths and weaknesses of correlations, 1.4.16 Controlling extraneous variables, 1.4.17 Planning research: reliability and validity, 1.4.18 Ethical issues in research, and 1.4.19 Dealing with ethical issues. Each one has a worked solution and a mark scheme showing where the marks go.