A researcher visits one sixth-form college in London and asks 25 students, face to face, how many times they helped another person in the past week. Most students report helping others several times. The researcher concludes that "British teenagers are very helpful".
Evaluate the validity of 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.