A researcher wants to find out how carefully people sort their household recycling. She visits 30 homes and asks each householder, face to face, how often they put items in the wrong bin. She hopes to show that most people sort their recycling carefully, and she smiles and nods whenever a householder says they never make mistakes.
Explain two threats to validity in this study.
173 exam-style questions on OCR GCSE Psychology 7.3 Analysing Research, covering 7.3.1 Types of Data, 7.3.2 Measures of central tendency, 7.3.3 Other descriptive statistics, 7.3.4 Tables, Charts and Graphs, 7.3.5 Reliability, 7.3.6 Validity and effects on validity, and 7.3.7 Sources of bias. Each one has a worked solution and a mark scheme showing where the marks go.