A researcher tests a concentration exercise using pupils aged eight to nine, then claims that the results apply to people throughout their lives. Hoping that the exercise will be successful, she gives its instructions with extra enthusiasm and encouragement but reads the comparison instructions in a neutral tone. Identify two different sources of bias that could affect 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.